Blow first, then just use a micro-fiber cloth, twist up one end and start wiping. Change corners of MF cloth as you get into other corners. I'm assuming you're referring to the external viewfinder lense?
If you do want to send it in, I doubt if Nikon will be willing to service a Canon camera for you.
It seems that the dust is inside the view finder when i through it. I tried using a blower and also a cleaning brush, but it doesnt work.
When i took some shots, the thick dust is not seen. So I guess Im pretty sure that its not due to the lense tat got the dust.
If it is too disturbing for you then send for CSC (not NSC ). I also had some dust specks in the VF, after a while they were gone again. Since neither your camera nor your lens are airtight you'll have to accept the presence of dust. But as long as the dust is not on the sensor or the rear element of the lens it won't affect the picture.
Dude... Then be sure to send it to the Canon Service Center at Harborfront.
It doesn't affect your picture quality, and will be a recurring problem even after you get it cleaned. But hey, if it really bothers you, send you camera for general servicing. That should clear it up. I believe its free if your camera is still under warranty.
The focusing screen is located inside the camera's mirror box, the matte piece of plastic along the light path to the viewfinder. So it's not directly exposed, unless you start sticking things into your camera. Never try to touch it with your fingers (or even a cleaning cloth, for that matter) because it's an extremely delicate piece of equipment and is easily stained and scratched. If you want to clean it, use only a blower. If it doesn't work, leave it alone (it won't kill) or let the pros do it for you.
If it's scratched or stained, go the service centre and get it changed there. It shouldn't cost much more than $20 odd dollars.