They're not in the XP format by default, no. If I remember right, the only difference with XP is that there's an extra column for the idle frames-- I THINK that if you just copy the middle frames into a fourth column, they would work for XP.
ahh -- IIRC the tilesets in RMXP don't have a size limit vertically, justkeep them the right width (idr exactly, but check the RTP and matc that) and you can extend them downwards infinitely...?)
