[How to set the Sleep Detection button on latest firmware (2.5) & GUI?]

I've upgraded one of my flircs to the lastest 2.5 software and enabled the sleep detection in the advanced setting as I did this. My understanding is this will allow only a single key to wake the htpc (rather than any key - which is the default).  

However how do I set which key to use.   (i'm using the flirx xbmc on my harmony ultimate remote - so would like to set - 'select' only to wake the htpc).

 

Thanks.

[Firmware 2.5 and Harmony remote and flirc profile]

I'm using a harmony ultimate remote and have setup the 'flirc xbmc' profile in the harmony.com settings.   However I previously used flirc for a different remote and the instructutions in this thread 

mention that it should be all ready to go however - it's just has the profile for the last remote.  how to I get it to work without setting up the remote manually in the flirc GUI?  - do I just clear the current configuration and it will be ready to go?