Start here:
http://forum.ppcgeeks.com/showthread.php?t=20492
Download and install BuildOS. Then run the updater to get the latest packages.
Hold down the power button and the record button then press the reset to put the phone in bootloader mode. Write down what version of bootloader you are using. Reset the phone.
In BuildOS, select your Cell carrier and select the version of bootloader that you have.
Now you select what to install. I would suggest starting with it stripped down. Flash it, and see how it does. If it works well, try adding a couple of programs and flash it again. Keep doing this till you have a ROM that you like and runs properly.