There are currently virtually no records from Volochysk in the JewishGen Ukraine database, outside of a handful of people listed in the Vsia Rossiia business directory and a few cases of people from Volochysk who are mentioned in the vital records of other towns and cities. Maybe Alex Krakovsky's wiki will eventually have more; at the moment, I think the only Volochysk records on his wiki are from a census list covering all of that district. There is also some good info on the Volochysk KehilaLink.
Pidvolochysk was part of Austria-Hungary until World War I, and consequently many of its records have been translated and indexed by JRI-Poland and Gesher Galicia, where they can be searched.
Adam Turner