I'll let you know because I just had one of these delivered and hoping it still works with BT4. It's suppose to be easy to mod which is what I was hoping for but I'll try it out first to see if BT4 even works with it.
Here's where I found the instructions on the mod with pics.
Jon Trent Adams - Phoenix WiFi
This USB was bought out by realtech so alot of the mods out there aren't the same cause the board changed.