Creating Apple Loops with Transients Intact

I was wondering if anyone knew of a program or something that can batch process about 1,000 .wav files, convert them into .aiff, and put in transients in thus creating an apple loop which then you can adjust the tempo to be used in GarageBand? I have used the AppleLoops utility, but for some reason the transients in the .aiff loop I created didn't seem to work when I adjusted the tempo in GarageBand

All suggestions are appreciated!

not very sure about this, but couldnt you try it in automator?