Are you sure that the seal is bad and you don't just have a piece of dirt stuck between the seal and the slider? How bad is the lead? Is it just fluid on the lower part of the fork or a puddle on the ground?
I had the same issue, and after a couple tries with a piece of film (you remember, that stuff we used to use to take pictures?) I was able to dislodge the dirt and have been riding happy with no leaks ever since!
You jsut have to take a piece long enough to get a good grip on and slide it past the outer dust seal and between the actual seal and the slider and make a couple swipes. If you don't slide the outer dust seal down, you will still have some fluid between the two seals that will make it seem like you still have a leak. I found this out the hard way and after ordering seals and all the tools to do it myself, the leak stopped. My leak was small enough that I wasn't worried about the fluid level in the fork. With a larger leak, this may be an issue.
Motion pro also sells a little card that does the same thing:
Motion Pro - Sealmate Fork Seal Cleaner (Each)
Keep in mind that if you do change the seals yourself, the manual only has instructions for the SP1 forks. The SP2 forks are different and not covered at all in the RC51 manual (thanks Honda!). If you do a search on here you will find some information, but mostly people saying send them to dan kyle racing. That isn't a bad idea if you are going to have a shop do it because for a little more money you can get some nice upgrades while they have them apart, and apperently dan kyle is the man when it comes to the RC.