is this what you need?
http://www.eq2flames.com/assassins/5...-advice-2.html
For the /assist... make this macro:
/alias assist_tank:assist %t
target your tank, and then click this macro.
Now, create a new macro:
/assist_tank
using the /assist_tank macro AFTER clicking the "/alias..." macro will target your tanks target...
basically, when you type /alias <command name>:<command to do>, it saves the command name and assigns the string of command to do against the command name, statically..
So clicking the alias macro when targetting Tank1 assigns "/assist Tank1" to "/target_tank". Then, when you click the alias macro again, targetting Tank2, it assigns "/assist Tank2" to "/target_tank".