I have an O.CT ecu on a 2000 S4 that I can't to get to connect with Lemmiwinks. Will pulling the instrument cluster fuse actually work? Will it screw up my car, or can I just clear the code with my vag-com afterwards?

The revo documentation suggests the following:
"The KWP2000 protocol is not as reliable as the VAG protocol. Some cars will have communication problems which often can be worked around by pulling the instrument cluster fuse (make sure VAG-COM will be able to clear you air bag DTC light before doing this!!!)"

But I rather doubt that pulling the cluster fuse on an S4 will solve your problems.

If you're running virtual com port drivers with one of our USB interfaces, try cranking the latency timer setting down to 1ms.

-Uwe-