I had Torment working perfectly with no hiccups whatsoever on both an iMac with an 8800 GS GPU and MacBook with a 9400m by using the bit depth workaround described in both the forum and tips section (having to set the monitor to thousands of colors before starting Crossover). However, the updated graphics card drivers that came with the Mac OS X 10.5.6 update appear to have broken Torment completely -- immediately after applying the update, Torment stopped working on both my iMac and MacBook.
The game crashes on start with an error message along the lines of "Assertion failed: no valid video modes supported". Googling this error has turned up that it's basically related to monitor resolution and/or bit depth and says that it couldn't set the monitor to a supported config (thousands of colors at 640x480 if you're not using the widescreen mod or a variety of widescreen resolutions if you are -- I was using 1280x800 with no issues). Manually setting my resolution and color to any number of allowed resolutions did not fix the problem, nor did reinstalling the game, with or without the widescreen mod. I tried a variety of other fixes through Wine that met with no success. I've just upgraded Crossover to 7.2 (from 7.1.1) and can confirm that the same behavior is present. At this time I'm aware of no way to run Torment through Crossover on OS X >= 10.5.6. If anyone can contradict me, do post your solution here. Success may also vary depending on your GPU; I'm aware of someone with an original MacBook (with GMA 950) that wouldn't run Torment even pre-10.5.6.