Answering my own question .... I found them under the Railroads system tag, which I think is a tag particular to New Jersey. (There is also one for New York state too, which is a little confusing.)
I may attempt to create a Custom database just with these frequencies, so I don't have to scroll through all the systems to find it.
Addendum: Learned today that there's a Railroads tag on the RR Database for just about every county in the US. I didn't have to create a Custom database in the HP-1 afterall. Instead, just copied the appropriate Railroads tag into a new Favorite I set up on Sentinel. Then transferred it over to the HP-1.
Last Edit: 26 Jan 2012 01:44 by juan m. Reason: Adding additional information.