There has been alot of discussion on this lately. As a rule, you don't have to do anything to the o-rings on the buttons. If you rinse your housing thoroughly...this means a good swishing in fresh water, pushing all the buttons several times each...that is sufficient to keep everything working.
There are no Olypus service centers in the States, not sure about other countries, that will service these cheaper housings. Even if there were, the price it would cost to clean and lube the o-rings would not be worth it. With the price of Oly housings so low, it would make more sense to just buy a new one.