I don't think the TIP shift knob mounts in the same fashion as the manual knob, but it would be interesting to hear if anyone's tried it. I personally wouldn't want to install a TIP shift knob in my manual car because 1) there's no shift pattern visable (in case anyone else has to drive the car, I don't want them throwing it in 1st when they think they're going into R!), and 2) I don't want people to think I have a TIP. LOL!
EDIT: The TIP knob mounts differently, as it has a spring loaded button that needs to release the knob from the shaft:
http://www.renntech.org/forums/index.php?showtopic=21053
The manual knob just presses on/pulls off if you have the standard issue knob, and presses on w/ a set screw to secure, if you have any of the upgraded aluminum/carbon/leather Tequipment knobs.
I installed a 987 manual shift knob to my 986, and really like the feel/look....