I wanted to figure out the same thing, guess I gotta do some searching and reading on how to add a oem to a kitchen. It'll probably take me days..lol
I'm currently running Psyki's newest rom that has the new 2.1 manila and mms works with cricket after editing the server settings and registry keys. I didnt try it with carrier cabs or Arcsoft cabs since it already has the latest arcsoft cooked in.
SSK's rom has working mms, and has the accelerometer working in pic mode. It uses the previous manila version though, but I was able to install the new manila on top of it with a few minor issues that were worked out with a few registry edits or cabs. That SSK rom needs the HTC_Guardian file removed or replaced with dummy file before setting up a cricket connection. I had to learn the hard way.
Here's the link to the oem and cab versions of the new Manila
http://forum.xda-developers.com/showthread.php?t=542113