@CyKoDeLiC: What knc1 said, plus, you mentioned a Kindle
4, while Komic is built around a framework only available on the K5 line...

. (This should be completely unrelated to the KUAL issue you're currently experiencing, but thought it worth mentioning

)
EDIT: Neeeeeeaaarly fast enough

.
That said, the KUAL extension *should* (I haven't checked) at least display properly on the K4, even if Komic itself won't work.
As for an alternative, without a format shift, nope. With a format shift, check AcidWeb's stuff in the main Kindle forum, you might be satisfied with that (KF8 files specially crafted to make use of the Kindle/KF8's comics/manga capabilities).