You could probably create something very similar to a click castsequence from the pre-Cataclysm warcraft.
Not sure that you should, given that was removed from the game.

Mercurio and Toned have several macros in two sticky threads, and Aragent has an IS Boxer thread for "two-step" macros.
Basically set up IS Boxer, so you have a hotkey which alternates between two outputs.
Have a castsequence on each, one for things that have a fixed reuse/recast time and will never 'stick' or get stuck.
And another for proc type effects, which you want to use whenever they're available.

http://www.dual-boxing.com/showthread.php?t=32633
http://www.dual-boxing.com/showthread.php?t=33870
http://www.dual-boxing.com/showthread.php?t=32456

The two-step macro approach has worked very well for a lot of boxers.

You could also go with something similar to Mosg2's DK Manifesto.
The pseudo priority sequence...
My text version (which has links to Mosg2's video versions if you prefer that): http://www.dual-boxing.com/showthread.php?t=37658