Do not apply or use any oil lubrication on the crankshaft rear oil seal or the seal installer. Do not touch the sealing lip of the oil seal once the protective sleeve is removed. Doing so will damage or deform the seal.
Clean the crankshaft sealing surface with a clean, lint free towel. Inspect the lead-in edge of the crankshaft for burrs or sharp edges that could damage the rear main oil seal. Remove any burrs or sharp edges with crocus cloth or equivalent before proceeding.
Also, did your replacement seal come with any text on it like 'this side out'? I know that in the smaller v6 engines, the rear main seal was revised and the new seals were installed reversed from the old design with the lip in.
There is also a special seal installer (J-35621) that makes installing the new seal much easier and sets it to the proper depth.