I use a G15 keyboard. Have 3 buttons all next to each other, left is mount, middle is jump, right is follow. So I hit the mount button, then the jump button so all toons become airborne, then hit the follow macro to get them all heading in the right direction.

A problem I have every so often when flying is the characters won't load on certain toons. This is especially bad when one of the alts can't see the main anymore, breaking /follow. This happens pretty consistently when flying, probably due to the fact that I'm moving around at close to 300% walking speed. Not sure if it's a network issue or what, but it's happened on all the different boxing setups I've used.