Here is the link for NJ Archive series will abstracts.http://search.ancestry.com/search/db.aspx?dbid=2793
Just type the name Hendershot and check out the ones from Sussex County. I see one from 1793 (not 1792) that might be your man. Will written January 8, inventory taken February 9.
If you find an abstract for the man you seek, then you can get a copy of the original will itself and the inventory from the NJ Archives in Trenton. Note the file number at the end of the abstract (560S). Include that number when you order. Or better yet, send them a photocopy of the abstract.
Wills were not kept at the county level until 1804, so there will be no record of this in the Sussex County office.