|| Unplug the factory sender and unscrew it.
||Take it and your new sender with you down to the hardware store, and buy a brass plumbing tee (mine's out right now and it looks like it's female 1/2" pipe thread) and a male to male coupler to screw it in where the factory sender was. My VDO sender was the same thread as the factory sender, and required no adapters; if you have a different size you may need a coupler or adapter.
||Use some teflon paste and install the tee and both senders
||Plug the factory one back in so that the idiot light still works.
|| Now run the wire for your new gauge up the front of the block, over to the driver's side of the firewall, and through one of the factory grommets (the one beneath the brake booster is fairly easy to get to).