PageFilter methods (and ACL)

I'm trying to do some custom page access controls, and I thought it 
might work to add some custom ACL text to a page using a PageFilter.  
I've tried adding something like [{ALLOW view tim}] to the end of the 
content using the preTranslate method, but it doesn't seem to work.

Any thoughts?  Is this even possible?  Should I try a different method?

Thanks a lot.

--
Tim Koop