For people living outside Japan, there are 3 methods:
1.) Using a credit card with JCB logo. But then not everybody has a JCB card. VISA & MasterCard are still more popular.
2.) Bank transfer. This is a bit of a long process. I've tested it myself for Dopyu's MOTONARI using an online remittance service that helps me send money abroad. Just make sure to input all the correct details. However transfer fee varies depending on your country & rate. The transfer itself was pretty quick (1 day), however the receiving bank took some time to recheck. Don't forget to notify HUNK-Ch by email about your transfer (I use both English & auto-translated Japanese). They're quite responsive. Overall it took me 5 working days from transfer to getting the points.
3.) Create a BitCash account (which anybody anywhere can do), buy a physical BitCash voucher if it's available in your country & use it to purchase HUNK-Ch points. Another fellow dweller of this thread has told me that they bought the vouchers from an online shop. I've also checked my local online shops & they're available, albeit a bit more expensive.