Now that BeyondMedia is officially discontinued, the ability to switch back and forth between another HTPC package becomes necessary. The nice way that hitting the "exit" button (ESC on the keyboard) on the BTV home screen pops up BeyondMedia should work with other HTPC packages such as MediaPortal or Meedio/Medios.
At the moment, you have to work around this missing feature by linking another button from your remote control to some actions that bring up the HTPC package (using Girder, HIP, LM Remote Keymap or the like).... it works, but does not flow as nicely as simply hitting the Exit button once more... gives it a more polished feel.
I created a feature request in the beta site, please vote if you think this is a worthwhile feature:
http://beta.snapstream.com:8080/browse/BB-1753
I think with a small amount of configuration, this might be a pretty straight-forward feature to implement given that BTV/BTVLink already has to find the BeyondMedia window and then make it active... Hopefully, it would be a matter of letting the user configure the WindowClass or WindowTitle to make active.
Geoff