Am I missing something? There's no way to withdraw USD from MtGox into OKPay. If you have some way that isn't obvious, please do share.
https://mtgox.com/trade/funding-options -- from this page I was able to add OKPay as withdraw method for USD.
Well, I feel like an idiot. Added. Question - how long did it take for them to validate yours as a withdrawal method? I'd really love to take advantage of the current spread between the two...