Several people using the Deep Sky Stacker software report success in stacking frames taken using Alt-Az mounts. I would guess that other stackers which, like DSS, use triangles of stars would also work. The triangle-based stackers can accomodate frame rotation. DSS requires star trails to be short so you still need short exposures. Stackers intended for planetary work, such as Registax6 and Autostakkert!2 would probably not work well (although Registax6, I believe, also uses triangles) and those based on fourier transforms could not handle the frame rotation.
Regards,
David Perkin.