Just a few thoughts from a SynCE hacker.
http://www.synce.org/index.php/Windows_Mobile_2005_HCL
Don't rely on this. Use of usb-rndis-lite is preferred in all cases, and if it doesn't work we need to know so we can fix it.
In Ubuntu, i strongly suggest against recompiling the kernel just for usb-rndis-lite. It just isn't needed! Instead do this:
The SVN driver has the added bonus of letting you access the internet via your WM6 phone. There are no difficult patching steps to get wrong either.
The best people to help you with SynCE are the SynCE team, so i look forward to seeing you in
IRC or the
mailing list.