Access to the IOM ferry is quite straightforward. They have recently renovated that area of the waterfront to accomodate major cruise liners as well as the usual ferries to IOM
If you are travelling from Worcester, I assume you will be travelling from the south end of the city - then follow signs for the Strand; the Liver Building is the last of the three major buildings on the waterfront from that direction and veer off to the left at the end of the Liver building and the ferry terminal is there.
It is to the side of the Crowne Plaza hotel
Anything else just ask