McGeechan has been speaking with Gatland this week and they have reached an agreement over how Edwards, the Wasps head coach, will split his time.
All that needs to be completed now are the details of a release contract, which is being discussed by Wasps and the Welsh Rugby Union.
McGeechan said: "It is moving on and I think it will be sorted fairly quickly now.
"Gats and I have spoken quite a lot this last week and we have agreed between us how it will work.
"The aim is to give Shaun extra experience and he can bring that knowledge back to the club. It won't be doing anything detrimental to the club, which was also a priority."