I FINALLY got the keyboard to install in /system/app without FC every 3 seconds and managed to get it themed.... woohoo!
I had to install Clicker.apk and HTC_IME.apk via Astro first, then I pushed HTC_IME.apk from my PC to /system/app without uninstalling the one I installed via Astro, and then reinstalled it (when I pushed it, it became uninstalled... not sure why). After that, it worked. I'm not sure of the logic behind all this. All I know is now it works!
Tried out the dark with transparent background... worked fine for me. However, I preferred the look of the regular with transparent background for now. Can't wait to see some more themes come out