I dont know if anyone has tried this before but I learned this type on a dirt bike forum and it works great. Take the old fork seal and cut it in half with a hack saw. Then you can twist it and put it on the fork to use as your seal driver. Just give some good wacks around it with a dead blow hammer and it'll be seated in no time.
I have done this before on my 2205crf450r, I just left the old seal on then used it to hammer the new seal in then just cut it off. worked like a charm.