Is there an easy way to run a HP500 EFI on the ground so I can set timing and break it in without installing in boat? I've seen it on youtube but not sure what all it takes. Thanks

Set it on a stable support (wood, tire, engine stand)
Hook a hose up to the intake side of the seawaterpump (some creative fittings from Home Depot)
Hook up a container of fuel to the fuel/water separator (easiest if gravity fed from above but not necessary......outboard fuel tank with bulb pump works great
Hook up juice to starter and hot wire on harness.
Use remote starter switch

Fire away!

Hot wire on what harness? This is the part I don't know. Where do I run the hot wire to??? Thanks

You will have to power up the #5 pin ( purple wire ) in the harness plug. That will supply 12 volts to the ecu, ignition, etc...When done correctly, you will hear the fuel pump turn on for a couple of seconds. Pulling that wire , will shut down the engine. It will most likely be easier to jump the starter slave solenoid on the engine, rather than jumping the solenoid on the starter. One false move down by the starter will fry your 90 amp fuse.