Blind transfer with single Zap channel


I’m an asterisk newbie running the latest trixbox 1.1 with freepbx 2.1.1 on a box with a single Zap channel. My goal is to turn my asterisk box into a generic automated attendant for my analog PBX. If my analog PBX gets an incoming call from the outside to a specific extension, the call is routed to the asterisk box which answers with an IVR. This much works. The part I can’t figure out is how to allow the caller to dial one of my many analog PBX extensions while in the IVR and have the asterisk box transfer the user to that extension out the same Zap channel (blind transfer?). I’ve dug around alot on Google and on the Trixbox and FreePBX forums and documentats and haven’t found what I’m looking for yet. If anyone could help get me headed in the right direction, I’d sincerely appreciate it.