No short cut to achieve nirvana in such a short time. It all boils down to constant practice and hardwork.
If you are really interested in learning keyboards, you can always sign up for keyboard lessons at Yamaha. It's best to have someone guide you in your keyboardmanship.
Since I'm into metal and I play the keyboards I'll tell you what I observed in how keyboards are used in metal music.
Since you're into power metal, I suggest you listen to lots of baroque classical music as epic power metal bands like Rhapsody and Masterpiece etc have lots of baroque music influences in them.
Keyboard solos in metal may sound complicated due to the fact that they are played fast but most of these keyboard (excluding Children of Bodom's) solos are merely ascending or/and decending scales with a few sharps along the way. Best way to go about doing it is to practice on your scales and I really mean practice on it. Spend like 15 minutes practising your scales, may seem really boring but trust me it really helps.
For a start you can go to ultimate-guitar.com and download the guitar tabs of your favourite metal songs. If the song has keyboards in it, you can practice along to the scores if you want. If you can't read notes you can look at the keyboard digramme above the scores.
Hope that helps but at the end of the day you need to sit down and practice, no shortcut.
