I'm definatly no expert, but I might be able to help.
Dave--
I'm not familiar with the area you're talking about, but your question depends alot on what species you're looking for. The salamanders you found in North jersey were probably redback salamanders which--as has been previously stated--you can find under almost any clutter or leaflitter. They're not as easy to come by as in north jersey, but they're definatly there. One good rule of thumb is that you're alot more likely to find them under a log in the middle of the woods than you are under a piece of plywood in an open sandpit.
Any other salamander you'd find in north jersey is pretty much nonexistant south of monmouth county, so i wouldn't count on any of those. The few species tolerant to the low pH in the pines are pretty scarce as well---and at that you'd have to know about a specific breeding pool.
As far as redbacks . . . with the weather we've been having this winter (mid 30's-high 50's) you shouldn't have problems finding them and dont' really need to worry about disturbing them---as long as you make sure to replace the cover (log, trash, whatever) exactly how you found it and leave the animal where it was found also.
Also--be careful not to handle the salamanders with your bare skin. Their porous skin is their only means of respiration and will absorb whatever is on your hands--so the natural oils and unnatural chemicals on your skin (soap, cologne, nicote, etc) can really harm them.
-Bob