Your going to have to do a search on that one, as Overload suggested, hopfully with pictues. Gironda was very detailed as to how that dip was to be done. Just like on his idea's on the Scott bench (really Gironda original idea), chin's and sissy squat's (great exercise & stretch...wonder if any one does these anymore?). I think you can still get some of his old manuels, on training, on Ebay.com. Anyway might try a Dogpile, AltaVista or Google search.
If your gym (or you) have a pair of 360 degree handle on a dipping bar or a set of 'V' bars (again suggested by Overload) your in luck. Good Luck.