So I spent the better part of tonight making an application as a go-between for GameEX and Steam. The idea is that it can be run standalone and get all the required information/media for your game and then it can be run with command line parameters to use the steam protocol (steam://run/appid) to launch games (even non-steam games that you added to Steam). When the game closes, my app does as well meaning GameEX immediately grabs focus again.
It also downloads Movies, Title Images and Screenshots for snaps. This means even if you already have Steam setup in GameEX (or any frontend, for that matter), you could use it to get this media.
Anyway I'm still working on it but I'm excited enough and tired enough to share this video and hope that maybe someone out there will want to use it soon! BTW, it's rough right now but I think it shows the software off pretty well.
1:25 to see how to use it to setup a game
3:18 to see how it grabs/previews media
5:00 to see it run from command line
5:54 to see how to set it up in GameEX
8:00 to see it working in GameEX (goes into game at 8:20, goes back to GameEX at 8:40)