It sounds like you have never done this before, so first, get OEM seals, I think almost everyone so far as agreed that the aftermarket ones are junk, and if you go that way to save money, you will be replacing seals more often. The saying " YOU CAN PAY ME NOW, OR YOU CAN PAY ME LATER" comes into effect here. Do it right the first time. Also order the Seal-Savers. I am a believer in them and if you wash your bike regularly, it will help keep the dirt out of the seals also. If you have a Yamaha owners manual, or find someone that does, their manual explains the process, with pictures and diagrams. As far as getting the new seals in, I took a piece of PVC pipe, cut it down the middle and set each piece around the tube and very carefully tap it down until you can get it past the slot where the retainer clip goes back on. Don't mess up the tube when you are pounding or you will get leaks that you will never be able to stop.
I don't have seal driver but I did have some left over lead flashing ( lead strip about 6-8" wide ) and I cut off the right length to go around the slider and it worked a treat, although I did wrap the slider in masking tape just in case, but probably not necessary to do this as chrome much harder than lead. Also of course if you have a roll of lead flashing its infinitely adjustable, you just cut off the length you need when you get a different bike instead of having to buy new drivers. Just be careful when wrapping it around the slider that its a nice straight edge facing the seal.