[nyc999]

This is somewhat read-dependant. Villain is starting with t645 - obviously played a few hands, were you able to determine calling ranges and evaluate post-flop play?

Without reads, I think it is hard to put villain on a flush. What would you limp with and then call a 5x raise with? AQs or maybe AJs, but would you expect the villain to limp with AQs? And I think a set is very unlikely (with 88 being the only real possibility).

I would put out about a pot-sized bet on the flop. I think on the turn when villain bets, you need to call. You will win often enough to make this a profitable play. Even if you lose, you have enough chips to work with.