You don't have to use Alt-F5 to do that, you can also just enter the chord like you have shown above, so if you just want the bass, drums, and guitar to play, instead of using Alt-F5 you could just enter the chord as: Em.bdg (for an Em chord)

That will hold until the next chord change, so if you have a few bars of Em you are good. Next chord change, if you still want only those three instruments to play you need to enter it in the same manner, Am.bdg for an Am chord for example.

A little faster than using Alt-F5 once you have memorized the shorthand.