..Hiee..
Too bad, most of the camera nowadays are using modular viewfinder, which may not be able to be cleaned without tearing apart the whole view finder assembly.
Some even have periscopic viewfinder which may make it more difficult to disassemble.
So.....i think you need to live with it or maybe send to the service center to have it cleaned. Try calling them.
.....i'm sure they aren't expensive to have it cleaned .
regards,
me