TMobile WiFi calling with rooted/stock android?

[SharksFan1]

I just got my first Android phone! But I've heard that the stock Android build is a lot better than TMobile skin, so I wanted to root it and put Froyo or Gingerbread on my phone. My one issue is I like the TMobile WiFi calling app, but TMobile says they dont have it for download on the Android market. Is there any way to get get the TMobile App on my phone if I put stock Android on it?