Step:
1) Buy RP with daddy's CC
2) Use them in LoL.
Much easier.
FTFY.
Realistically, from a Bitcoiner's perspective I can see why you'd want merchant acceptance - but from Riot's view I can't see a reason at all to accept Bitcoin transactions.
Well I'll give them a reason then, I'm a platinum player in LoL, but I've never bought RP, since it's not a pay to win game, there's no reason to buy, RP is only for buying skins. Everything else in the game can be obtained for free. Plus, I try to keep my credit card usage online to a minimum, to minimize the risk of information leak, especially since gaming companies doesn't have the greatest track record of not being hacked.
But if Riot start accepting Bitcoins, I pledge to buy at least 1 BTC worth of RP.
Maybe this sort of this should happen more often to entice more merchant acceptance of BTC. Send BTC to an escrow fund, show a company how much is pledged if they begin accepting BTC as a payment, and when BTC is made a payment option, release the funds for transactions. Sure the logistics would need a bunch of fine-tuning, but I could see this working.
Then again though, I think the pledged money needs to be fairly significant in order for this to work.