If you have an old king pin, that can be used as driver to push out the pin currently in the axle (this will only work if the entire mounting assembly and axle if removed from the tractor.).
If you have left the front axle bracket on the tractor, a large cold chisel can be used. Work around the circumference of the pin face, using the flat of the chisel as a lever. Heat and plenty of penetrating oil help if it's really difficult.
To remove the bushing, begin carefully cutting the bushing with the chisel. It will start to curl and should then push out fairly easily.
The new parts should slip in pretty easily by hand - or with a very light tap of a hammer.