Hi ElCharro,
I also have a PCI Catweasel MkIV.
In order to best help you with writing Macintosh and Atari ST images to DSDD floppies (both of which I have never attempted with my Catweasel MkIV, because I also have an ISA Catweasel card), I will have to reinstall mine.
I have two questions concerning your setup:
(1) What operating system are you using it with?
(2) Have you given the Catweasel a dedicated floppy drive?