I got the answer: there is no direct/easy way to do that, at least from what I've seen.
What I did:
a. I added a new custom filter control type, named "custom";
b. the aoColumns
would have the following definition:
"aoColumns":[
{ "type": "custom", "callback": fnControlCallback },
{},
{},
{},
{},
{}]
c. change the following function to look like this in jquery.dataTables.columnFilter.js:
function _fnRangeLabelPart(iPlace)
{
...
switch (aoColumn.type)
{
...
case "custom":
if (null != aoColumn.callback && undefined != aoColumn.callback)
{
fnPrepareForCallback(oTable, aoColumn);
}
break;
d. And then, the new function (same file: jquery.dataTables.columnFilter.js):
function fnPrepareForCallback(oTable, aoColumn) {
var index = i;
var s = aoColumn.callback(oTable, aoColumn, $(this));
var object = $(s);
th.html(object);
}
e. and the callback method would be like this:
function fnControlCallback(oTable, aoColumn, o) { return '<input type="checkbox">'; }
Hope it helps someone and saves some time. Thanks.