I'm not sure about Octopus, but Keyclone is the other software option for multi-boxing.
Keyclone works great for me, and the support for it is great; a one-time 20 dollar fee isn't that much, considering how much we spend already on warcraft.

If you want your G15 to work for both applications of warcraft, they either need to be run from the same warcraft directory, ie click wow.exe twice, or you need to click G15 Profiler - Settings - Profiler - Profile... and enable the 2nd option (Enable Persistent Profile).

Two melee classes is a lot harder then one melee, and as many ranged classes as you'd like.
I'm not saying you cannot do two rogue's, but it will be a lot of moving the master and then adjusting the slave.