It seems you can't, they only accept ethereum as payment. Moreover BCH is still a new coin, still not recognized as a payment method although the price is so high.

0x2EFC356D401cDc868461D5bb016f42eCE6dc2211
1 ETH = 300 preRocketCoin + 50% bonus
Token Symbol: preROCK, Decimals: 18
Gas Limit: 90,000, Gas Price: 50 Gwei