You can use a huge number of frames. To make things easier, you can store many frames in one line. Example:
frameset 0 43 1 0 0 0 NONE
So frames from 0 to 43 will be played with speed 1. Need to note that frameset can't execute any actions so if you need to execute them, make it like this:
frameset 0 43 1 0 0 0 NONE
frame 44 1 0 0 0 ATTACK (or anything)
frameset 45 64 1 0 0 0 NONE