A friend from the Reaper forum (the audio program) has made a midi mixer vst that can be usefull for GPO users. It can display what is your mod-whell doing in the 8 channels (really it has 16 channels, but you only will use the first 8) your pedal, volume, pan, and plus you can SEND messages from there. You can read about it, here:

here and screenshot:

and here the download link: