Hi, I am attempting to change my bcm on my 1997 voyager van. Any helpful directions

You'll need to know if your vechicle is equipped with Vehicle Theft Security System (VTSS)
You'll also need to stay within your vehicle's model year to insure feature compatibility (so things like lighting and wipers will work)
Since this is far from plug-n-play, the factory scan tool (DRBIII) will be needed to accomplish the necessary inter-module programming.