Go to backscatter.com, and down load their recommended setings for TG-5 with strobe.I have a TG-5 and the Olympus housing. I have been using it for the last 2 years, and have had some decent shots. I bought a Sea and Sea strobe and took it to Coz last February, but unfortunately it flooded on the first dive. I was able to revive it and am hoping to use it on our trip in 3 weeks. I am pretty clueless about the strobe operation though, so I guess a lot of trial and error is in store.
This is the one for Macro, they have ones for wide and video as well