[Chameleon] changing the FILTER map file parameter via URL

[dave thau]

Hello folks,

I have an application which retrieves coordinates from a postgis/postgres
database and plots the points on maps pulled using wms.  Everything works
great in chameleon, but I want to be able to let users alter the FILTER
via URL (like you can do with the mapserv cgi program).

Something like:

http://myapplication?map_myDataLayer_filter="foo like '%bar%'"

Is there a straightforward way to do this?  I can't find anything about it
although it seems like it would be a common need.

Thanks for any suggestions!
Dave