How do you set the timing on a 92 Nissan maxima 3.0 dohc?

loosen the distributor, have a timing light, preferably an adjustable one, and it should be 15 degrees +/- 2 before tdc.

***See what engine code you have. If it is a Maxima SE (DOHC)(VE30DE engine code) you will have a timing chain instead of belt and probably no distributor. The GXE (SOHC) has the VG30 engine which has the belt...