Multiple Instances of xbmc

Against all advice I'm successfully running multiple instance of xmbc in portable mode through XP by running each as a different user.
By giving different http port it working to play tracks and select from library and playlist...but.... the next track and volume control keep controlling only one of the instance (don't know how it decides which one)
I'm just assuming these controls are done though media keys or similar and this is the issue?
My first thought is to use virtual box to assign separate ip adresses but as this will needlessly consume more resources any have a suggestion to remedy this issue?

I suppose they are controlled by EventServer.

This is UDP port 9777 by default so only one instance can bind this port.

I can't find it but I think there's an advanced settings that allow you to change this port too, that would correct your problem.

Thanks, your spot on I thought I had seen it before but could not find.
It appears to have been removed from xbmc settings??
http://wiki.xbmc.org/index.php?title=EventServer

Found it in another forum, it's in GUIsettings
http://forum.xbmc.org/showthread.php?tid=125693

Not sure if it can be change via advancesetting so i just edited the GUI one

Working now