I don't remember the plug being that difficult buy maybe my hands are smaller.
I did have the car quite high so I could extend my arms up comfortably. There is a lock inside the tranny, you pull the tab down to remove the plug and push it up when the sleeve is installed again. It won't lock up if the sleeve is not all the way in.
If memory serves me correctly I tried to install the new sleeve with the wire harness attached with no success. I pulled everything back out, got the sleeve installed and the locking clip back up in place and then plugged the wire harness back in. It worked on the second try and I have no leaks. Hope this helps.
Sometimes on the second try everything goes in like butter and you wonder why it was hard on the first try.