The built in switch is cascadable, and can be used. Just run 2 lines from it (Any 2 lines, doesn't matter) into a 4(5)x8 switch. Then run 2 lines from your round dish pointed at 101 into the switch. I won't swear, but from my understanding (Very credible sources), all that would work fine, even if you were getting a signal from 101 on the triple sat, but since you're not even doing that there won't be a problem. Just make sure the switch you buy either says cascadable and/or 22khz tone.
If you need some more help (Not that I'm not having fun helping you out
), you might want to check out the dbsforums over at dbsforums.com It's where I get most of my info and help from.