yeah, its not a problem, just get a MIDI interface, a cheep one is like $30 USD. that hooks to your computer via USB then you get 2 MIDI cables that go from the out of the keyboard to the in of the comp, then from the out of the comp to the in of the keyboard. after a little fiddling (there has been numerous posts on how), Reason will recognize your Casio as an external syth, recording the midi notes played, and using the keyboard to play them back.
I dont know what you mean by 'run reason through it' as in your keyboard. there is no way to load reason onto the keyboard, you will always need a laptop to run reason. but you can use the casio as an external synth. good luck