DO NOT PUT ANY SEALANT ON IT!! They dont need it and are more likely to leak if you do.
A rear main is there to seal around the inside not the outside. You should never need to put anything around the outside of an interference fit seal like this.
Fitting it ... Admitedly, they are a unpleasant individual to fit with the rear bearing cap in place as they are very easy to damage. If the engine is out i prefer to fit the seal before torquing up the rear cap. That way you can just sit it in place easily with your fingers.
If you are doing it with the motor in the car you just have to be very patient and careful as you evenly tap it into place. In the past i have succesfully ground a leading edge on the engine side of the seal to help get it started.
Take your time and dont be heavy handed.
G