You can use
this guide as a template for what to properly put in the fields. Be sure to uncheck MDS boxes as those are used for BES users.
I just tried it and successfully retrieved my Gmail, however I was disappointed after testing to find out that it is NOT push nor does it properly sync like IMAP should.
The funny thing is, it allows you to configure From, Reply-to, and even signature fields (awesome!); however, replying or composing any email cannot be found in any menu function! This is not a very useful program.
Funambol is a little better, but also suffers from some flaws: some emails do get pushed, but not all. The syncing of the read/unread status is a little finicky since it's not really being pushed. It also lets you compose and reply.
I only tried setting up IMAP with these two apps. Perhaps POP might be better.