Did a little more "digging" on the site...  Apparently no need to pull the motor, or split the cases! 

Here's the fix i found from an 250R post

"remove the sprocket and spacer, take a screw driver and pop out the seal, while not scoreing the case.  clean out the bore.  use a socket and tap the new seal in.  put a little oil or blue loctite on the seal when you install it." 
similar to the shift shaft seal replacement!

I'll be trying it this weekend!  Fingers crossed for an easy fix!