I was unable to hit 115mm exactly. Here's one that will print at a little over 116mm on all three of my printers and from IE or Firefox. Adjusting the width to 19 gets you down to about 109mm...
I am using a separate png image for each symbol and stringing them together on the client side. The complete Code128
symbology using this technique can be found at http://notionovus.com/blog/barcodes/html/code-128-barcode/
<img
alt="104,{Start B}" title="104,{Start B}" src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAsAAAABAQMAAAAy+cYDAAAABlBMVEUAAAD///+l2Z/dAAAACXBIWXMAAA7EAAAOxAGVKw4bAAAADklEQVQIHQEDAPz/AC3gAT0BDuLeG4IAAAAASUVORK5CYII=" width="20" height="30"><img
alt=" 33,A:{A},B:{A}" title=" 33,A:{A},B:{A}" src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAsAAAABAQMAAAAy+cYDAAAABlBMVEUAAAD///+l2Z/dAAAACXBIWXMAAA7EAAAOxAGVKw4bAAAADklEQVQIHQEDAPz/AFzgAZsBPUCFhSIAAAAASUVORK5CYII=" width="20" height="30"><img
alt=" 34,A:{B},B:{B}" title=" 34,A:{B},B:{B}" src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAsAAAABAQMAAAAy+cYDAAAABlBMVEUAAAD///+l2Z/dAAAACXBIWXMAAA7EAAAOxAGVKw4bAAAADklEQVQIHQEDAPz/AHTgAcsBVYSvxaMAAAAASUVORK5CYII=" width="20" height="30"><img
alt=" 35,A:{C},B:{C}" title=" 35,A:{C},B:{C}" src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAsAAAABAQMAAAAy+cYDAAAABlBMVEUAAAD///+l2Z/dAAAACXBIWXMAAA7EAAAOxAGVKw4bAAAADklEQVQIHQEDAPz/AHcgAREAmJf+YHwAAAAASUVORK5CYII=" width="20" height="30"><img
alt=" 36,A:{D},B:{D}" title=" 36,A:{D},B:{D}" src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAsAAAABAQMAAAAy+cYDAAAABlBMVEUAAAD///+l2Z/dAAAACXBIWXMAAA7EAAAOxAGVKw4bAAAADklEQVQIHQEDAPz/AE7gAX8BL1PJL4YAAAAASUVORK5CYII=" width="20" height="30"><img
alt=" 37,A:{E},B:{E}" title=" 37,A:{E},B:{E}" src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAsAAAABAQMAAAAy+cYDAAAABlBMVEUAAAD///+l2Z/dAAAACXBIWXMAAA7EAAAOxAGVKw4bAAAADklEQVQIHQEDAPz/AHLgAccBU7KPeu8AAAAASUVORK5CYII=" width="20" height="30"><img
alt=" 38,A:{F},B:{F}" title=" 38,A:{F},B:{F}" src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAsAAAABAQMAAAAy+cYDAAAABlBMVEUAAAD///+l2Z/dAAAACXBIWXMAAA7EAAAOxAGVKw4bAAAADklEQVQIHQEDAPz/AHOgAYkBFLOchfoAAAAASUVORK5CYII=" width="20" height="30"><img
alt=" 39,A:{G},B:{G}" title=" 39,A:{G},B:{G}" src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAsAAAABAQMAAAAy+cYDAAAABlBMVEUAAAD///+l2Z/dAAAACXBIWXMAAA7EAAAOxAGVKw4bAAAADklEQVQIHQEDAPz/AC7gAT8BDxDJjdQAAAAASUVORK5CYII=" width="20" height="30"><img
alt=" 40,A:{H},B:{H}" title=" 40,A:{H},B:{H}" src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAsAAAABAQMAAAAy+cYDAAAABlBMVEUAAAD///+l2Z/dAAAACXBIWXMAAA7EAAAOxAGVKw4bAAAADklEQVQIHQEDAPz/ADrgAVcBG9SQg7wAAAAASUVORK5CYII=" width="20" height="30"><img
alt=" 99,A:{Switch C},B:{Switch C}" title=" 99,A:{Switch C},B:{Switch C}" src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAsAAAABAQMAAAAy+cYDAAAABlBMVEUAAAD///+l2Z/dAAAACXBIWXMAAA7EAAAOxAGVKw4bAAAADklEQVQIHQEDAPz/AEQgAKsAZaZph30AAAAASUVORK5CYII=" width="20" height="30"><img
alt=" 01,A:{!},B:{!}" title=" 01,A:{!},B:{!}" src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAsAAAABAQMAAAAy+cYDAAAABlBMVEUAAAD///+l2Z/dAAAACXBIWXMAAA7EAAAOxAGVKw4bAAAADklEQVQIHQEDAPz/ADJgAMcAkzbyVIUAAAAASUVORK5CYII=" width="20" height="30"><img
alt=" 23,A:{7},B:{7}" title=" 23,A:{7},B:{7}" src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAsAAAABAQMAAAAy+cYDAAAABlBMVEUAAAD///+l2Z/dAAAACXBIWXMAAA7EAAAOxAGVKw4bAAAADklEQVQIHQEDAPz/ABIgAEcAM15OsZIAAAAASUVORK5CYII=" width="20" height="30"><img
alt=" 45,A:{M},B:{M}" title=" 45,A:{M},B:{M}" src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAsAAAABAQMAAAAy+cYDAAAABlBMVEUAAAD///+l2Z/dAAAACXBIWXMAAA7EAAAOxAGVKw4bAAAADklEQVQIHQEDAPz/AETgAWsBJQmo7lIAAAAASUVORK5CYII=" width="20" height="30"><img
alt=" 67,A:{ETX},B:{c}" title=" 67,A:{ETX},B:{c}" src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAsAAAABAQMAAAAy+cYDAAAABlBMVEUAAAD///+l2Z/dAAAACXBIWXMAAA7EAAAOxAGVKw4bAAAADklEQVQIHQEDAPz/AHpgAVcA2+hRyrMAAAAASUVORK5CYII=" width="20" height="30"><img
alt=" 89,A:{EM},B:{y}" title=" 89,A:{EM},B:{y}" src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAsAAAABAQMAAAAy+cYDAAAABlBMVEUAAAD///+l2Z/dAAAACXBIWXMAAA7EAAAOxAGVKw4bAAAADklEQVQIHQEDAPz/ACQgAGsARQRcPq8AAAAASUVORK5CYII=" width="20" height="30"><img
alt=" 01,A:{!},B:{!}" title=" 01,A:{!},B:{!}" src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAsAAAABAQMAAAAy+cYDAAAABlBMVEUAAAD///+l2Z/dAAAACXBIWXMAAA7EAAAOxAGVKw4bAAAADklEQVQIHQEDAPz/ADJgAMcAkzbyVIUAAAAASUVORK5CYII=" width="20" height="30"><img
alt=" 23,A:{7},B:{7}" title=" 23,A:{7},B:{7}" src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAsAAAABAQMAAAAy+cYDAAAABlBMVEUAAAD///+l2Z/dAAAACXBIWXMAAA7EAAAOxAGVKw4bAAAADklEQVQIHQEDAPz/ABIgAEcAM15OsZIAAAAASUVORK5CYII=" width="20" height="30"><img
alt=" 45,A:{M},B:{M}" title=" 45,A:{M},B:{M}" src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAsAAAABAQMAAAAy+cYDAAAABlBMVEUAAAD///+l2Z/dAAAACXBIWXMAAA7EAAAOxAGVKw4bAAAADklEQVQIHQEDAPz/AETgAWsBJQmo7lIAAAAASUVORK5CYII=" width="20" height="30"><img
alt=" 67,A:{ETX},B:{c}" title=" 67,A:{ETX},B:{c}" src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAsAAAABAQMAAAAy+cYDAAAABlBMVEUAAAD///+l2Z/dAAAACXBIWXMAAA7EAAAOxAGVKw4bAAAADklEQVQIHQEDAPz/AHpgAVcA2+hRyrMAAAAASUVORK5CYII=" width="20" height="30"><img
alt=" 89,A:{EM},B:{y}" title=" 89,A:{EM},B:{y}" src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAsAAAABAQMAAAAy+cYDAAAABlBMVEUAAAD///+l2Z/dAAAACXBIWXMAAA7EAAAOxAGVKw4bAAAADklEQVQIHQEDAPz/ACQgAGsARQRcPq8AAAAASUVORK5CYII=" width="20" height="30"><img
alt=" 46,A:{N},B:{N}" title=" 46,A:{N},B:{N}" src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAsAAAABAQMAAAAy+cYDAAAABlBMVEUAAAD///+l2Z/dAAAACXBIWXMAAA7EAAAOxAGVKw4bAAAADklEQVQIHQEDAPz/AEcgALEAaE/9r8gAAAAASUVORK5CYII=" width="20" height="30"><img
alt="106,{Stop}"title="106,{Stop}"src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAA0AAAABAQMAAAA/57ZEAAAABlBMVEUAAAD///+l2Z/dAAAACXBIWXMAAA7EAAAOxAGVKw4bAAAADklEQVQIHQEDAPz/ADigARMA2dpJzT8AAAAASUVORK5CYII=" width="20" height="30">