If you want the cycle to repeat again (right goes into left, etc) then it gets tricky. I'm trying it now and not doing well with it. The Stereo delay in Amplitube works better I think.
Reaper is awesome! I'm still running the demo version. Have been for way too long. Buying a new car in the next few days and moving soon, but once that is over, I'm gladly and proudly going to spend the $60 or whatever it is for a license.
You could alternatively send the mono track to 2 sends set the wet to 100% and pan them accordingly. ReaDelay is great though. If you are looking for an incredible delay/echo check out echoboy. It's a little pricey but you will never need another echo plugin ever again