i wouldn't buy any special tools for installing seals.
just find something that is flat and square and tap the seal into place.
the cam and crank seals are not very hard to do.
the large rear main seal is a b1tch.
it is a large diameter and it is very hard to keep it square to the shaft.
but i don't ever change them unless they are really leaking.
they usually do not leak.
so i don't change them.
the common leak on the rear of the block is the oil separator plate ,
not the rear main.
it is not unusual for a rear main seal to last the life of the car, 300k miles or more.
you can't say the same for the other seals.