The TTL port on the CMUCAM2, both 2005 & 2006 KOP releases, works just fine. No jumper is required, but you can only have one of the three CMUCAM serial ports hooked up at any one time. Even loose wires connected to a TTL port, for example, will make that port look active and the CMUCAM2 board will get too confused to communicate properly.
You just have to make a special 4-pin connector that avoids the +5v pin on the CMUCAM TTL port and gets the Rx/Tx in the right order.
The TTL port got better coverage in the Vex forum:
http://www.chiefdelphi.com/forums/sh...28&postcount=7
Just modify the Vex controller side of the discussion to reflect the TTL pins on the FRC.
I'll echo Dave's comments on TTL & noise, actually any PWM cable and strong electrical fields. I'd suggest using shielded cable for TTL or any communication, but in any case monitor your final solution looking for susceptibility to noise especially if the cable is routed anywhere near magnetic fields such as those around the CIMs or alongside power lines.
We communicate with the CMUCAM via it's TTL port on our 2006 FRC robot, and we use the 2005 KOP CMUCAM (TTL port) on a Vex demonstrator robot. Several other teams I know also communicated through the direct TTL connection.
P.S. This thread would be more useful in the CMUCAM sub-forum.