As long as the other requirements for OneCare are met, I would think that it should work, but I can't promise it will. You will need to upgrade to SP3 of XP as it is currently listed as a critical/important update and OneCare will require this to remain Green. Also, you can use any browser, but IE must be updated to IE7, even if you don't use it.
You can certainly try with the trial from http://onecare.live.com regarding the use of progman.exe, as I have no experience using that as the shell.
-steve