Warning! According to George Irvine this is not recommended.
You may need the strap if you rip a seal on your drysuit.
I still have mine bungeed like this.
If I didn't use gloves and thick underwear, where the straps barely fit,
I probably wouldn't have put any bungees on the BT.
Remove the Uwatec.
Cut off the original straps.
Drill 4 holes in the bottom and 2 on the side.
Thread a one piece bungee through the holes and out on the side.
Adjust the length of the bungee and make knots on the outside.
Cut of the bungee and melt the ends.
Put in the Uwatec and you're done!