I assume you understand how to send a track to a send bus, then when you select the send bus and go the the left side of your screen where it gives you the detailed track options like volume and panning and there will be an option called "out". Make a new group track, route the "out" to this new group track, then go to your bass track and put the "out" of this track to the same group track. Now the bass will be send directly to the group track, as well as to the send bus which is then routed back into the group track.
So for mid and high splitting, send the same bass track to two different send tracks, EQ them on the send tracks and then use the "out" function to route them back into a new group track and add some final compression to glue it all back together. This is all from the head, I'm not at home so I could be forgetting something hahaa..