I use an 1/8" drift punch with the end ground to a sharp, 45 degree angle. I take the guts out of the gear housing, then put the shift shaft bushing back into the gear housing and mount the housing tightly in a vise. I find this to be the best way to hold the bushing, while I work to remove the seal. Then I carefully chisel the outer part of the seal in towards its center, until it is loose enough to pry out with a screw driver. Sometimes you can grab part of the pried-in edge of the seal with small Vise Grips and pry it out that way, too.
Long live American manufacturing!