Currently the game is only available for pre-download in the following regions : Taiwan, Hong Kong,
Macau, Singapore, Malaysia, Philippines, Indonesia, Thailand, Cambodia, Australia, and India.
Here's the link to go and register! http://event.capcom.com.tw/rxd/obt_0203/en-US.html
Here are the rewards depending on how many people get pre-registered! At the time of this writing the website reads 5,128 total registrations so far.
Besides the in game rewards you can also win real items by inviting your friends to register as shown below!