I asked the same question on the Portable apps website and got this response. It worked great although take note of the distribution license.
Add a text file called GoogleChromePortable.ini in your GoogleChromePortable folder that says
[GoogleChromePortable]
RunLocally=true
this will make it copy the profile to the temp folder on the computer and run from there whether it's in read only place or not.
also notice Johns reminder in Pyromaniac's thread (http://portableapps.com/node/37168#comment-207403) - giving someone, especially a "customer" a copy of Google Chrome, Portable or otherwise, is illegal, don't do it.
Link to forum
http://portableapps.com/node/37164#comment-207482
I've investigated the license agreement and found this
21.2 Subject to the Terms, and in addition to the license grant in Section 9, Google grants you a non-exclusive, non-transferable license to reproduce, distribute, install, and use Google Chrome solely on machines intended for use by your employees, officers, representatives, and agents in connection with your business entity, and provided that their use of Google Chrome will be subject to the Terms.
So legal as long as it's kept internal. Works great if anyone ever stumbles on this question. Chrome makes an awesome portabl app.