[/Follow] Is it do-able?

I just recently decided to update my leaders position manually on the followers client via the new_tick packet (and maybe the update packet as well). Should be better as I won't have to code anything into the client itself and it will handle movement interpolation between updates.

Adding packets to the client shouldn't be that difficult though and I'm pretty excited about that possibility. Like you said, the ability to bring in outside information to the client would provide for some interesting stuff.

I could see this implemented as an RPG'ish type command that allows you to follow a friend/party by Kabam.

This the exactly same command I was trying to create, but with no idea of how (naab).

I don't think you should aim so much for a complex script. What is needed is a command that "mirrors" someone who's in the fame train and maybe teleports to him from time to time (this way avoiding getting stucked). I'm saying this because if you stay on a train for like an hour, you will easily figure out who are the ones you could "/follow", because there are some players that fame farm 24hours/7days.

As Clearance~ says it's something more to use while multi-tasking or watching a movie, where you can manually re-enter the realms and choose another player to follow when needed.