unless you can figure out a way to get the old lug out, you'll have to pull the axle and hub off and take it to a press. Axle is actually pretty simple, but the hub is what you need. I've heard of using an open lugnut put on backwards with an impact to draw a new lug into place.
My website should give you a better idea of what's involved. If you do it, you might as well put new seals in and repack the bearings.
www.iluvrocks.com/fzj80_rear_bearing.htm