Ken,
The first thing to do is to get girder setup to execute the commands. Here is an example file that may be of some help:
http://webpages.charter.net/mfan/Example%20File.GML
In this example, I use a firefly remote to raise the volume of winamp or zoomplayer. Note that the volume up and down in each group are triggered by the same firefly button presses. This is a little different than you want to do, but will serve as an illustration. The key to making this work is to enable one group and disable the other. This is the purpose of the commands in the powercommands group. These 2 commands are triggered by girder events that you can associate with an event to enter, say, the music section of xlobby or the movie section of xlobby.
The order of events should be:
Set up girder groups of commands for each device (or state).
Set up girder commands to enable and disable the groups of commands.
Attach a girder command to an xlobby event to trigger the appropriate group enable commands at the appropriate time.
And away you go...
Don