Yep, it's not recommanded but in theory it's the same thing that when "you use the A1200 floppy power connector to power a 3,5" harddisk AND the floppy drive"...
Note that some IDE CF adaptor simply doesn't work on A1200.
Mach5 products works :
http://alan2.rateliff.org/a1200flash/http://alan2.rateliff.org/a4000flash/What's your model (reference ?) ? Type of molex connector ?
