It's actually pretty simple: It sounds like you have the X3 connected properly, you just need to connect another MIDI cable from the other MIDI output of the 002R to the TR-rack. Then it's just a matter of selecting the proper MIDI ports as the input and output of the respective MIDI tracks, and making sure you have the audio routed out from the hardware units into the 002r. You never said what version of PT you are using, but with versions above 6.7 in Windows, there is also another setup step you can go through (MIDI Studio Setup) to make selecting patches easier, but it's not necessary; it just makes things more convenient.

Thanks so much! I'll have to run down to the store and get another MIDI cable! I'm using PT 6.9. I'll have to fool around with the system and get familiar, I've gone into the MIDI Studio Setup, but I'm not sure if I've got it set correctly. Another problem that i have that seems to be common on the boards is (Reason especially) indicated that the MIDI ports are being used by another device. I tried the hook up without the TR-Rack and the light on the 002 Rack indicates a MIDI In signal but it stops there. Am I missing something in the PT MIDI setup. Sorry to be a bother, but thanks so much for yor help, I really appreciate it.

If you are trying to trigger reason, and you're using windows, you need to set up the external MIDI device on a Pro Tools MIDI track, and then trigger the Reason MIDI device from there. Pro Tools in Windows "steals" all of the MIDI devices when running.