I don't think it's possible with the current implementation of Canola's UPNP player. IIRC the canola team left off implementing control-upnp and only implemented the player in the current release. I could be wrong however, you'd have to ask handful.

If you need it now, I'd suggest mediastreamer, or if you can stand to wait, the next iteration of the UPNP plugin for canola will probably have controls implemented.

Again, this is just based off threads i've read around here i'm in no way associated with the canola developer's team and as such, my info may not be accurate.