I used Jamba, and it did the job I needed it to do
Where do I install Jamba? Only on the main character or also on the alt?

I did movement really simple. Only key that was "passed through" to another client was "W" - "qeasd" keys were totally ignored. Slave just made /follow main every time I pushed W. Basically slave was a trailer and main was a truck pulling it around. I noticed that sometimes I needed to turn both toons which was pretty clumsy with only follow so I used arrow keys to move both toons forward/back and turn them. Might not be the smartest solution, but worked for me.
That's exactly what I'm doing right now, tough, I'm having problems trusting the /follow while walking in a city, near a thousand of obstacles he could get stuck in =/ that's mostly the reason really

Thanks so far - Going to try Jamba =P