Had the same prob, but i'm i just using a cheap usb mouse as a workaround. I haven't put the time and efford into looking for a fix yet.... ***Although*** there ARE some nice guides in the ubuntu forum about getting everything on your mac (for the most part) working in a linux env. .... I know it's not backtrack, and i haven't looked at it since i switched to bt, but i might work because it's a fix for linux. .... i dunno, worth a shot.
P.S. I'm running a MBP 15" (2nd Gen) 2.16 ath card, ati x1600, everything (for the most part) works fine for me. .... Injection worked RIGHT OUT THE BOX OF BT!!!! .... no patchs, no work around: Put CD in, Boot, Open Terminal get cracking! ;^)