I have a setup similar to what you're trying to achieve... In Draenor you need to complete a bunch of tedious chores to acquire the ability to use flying mounts. I've only done this on my first Battle.net (that God it's B-net wide), and just use a simple setup to pop toons on my second B-net on 2 seater mounts so I can fly around.

I'm sure there are multiple ways of setting it up, but I chose to do a single mapped key with 2 steps.

Step #1:

- Toons on B-net #2 execute a simple /target macro to acquire the right targets (ie: the toons they will be "mounting") You can either make the macros ingame, or in Isboxer
- Toons on B-net #1 mount up on 2 seaters.
Step #2:

- Toons on B-net #2 use IWT


As far as I know there is no way to use IWT through macros, but there also is no need to be doing that.