I think what you need is no different from 2 step macro.

Never used Octopus, so can't advise on the setting needed. But, the post by Dancock may solve your problem

http://www.dual-boxing.com/showthread.php?t=34310

It basically changes action bar whenever you press the designated key, and thus you get macro 1, macro 2, macro 1, macro 2, ...... I didn't use this method as I am using script based AHK. Those have adopted this method seems to love it.

Good luck, and have fun. Let us know if your problem is solved or not.