Right, I haven't read the 'how to' lately but, here's what I did:
Run a length of 30 amp cable from the battery, to the new relay, located next to the fuel pump cover. This should have a fuse no more than 12 inches from the battery.
Connect this to pin 87 of the relay. This is the new power feed for the pump, not the relay switching feed.
Cut the stock live feed at the fuel pump plug, and solder a length of 30 amp cable to the cable at the plug end. Solder the other end of this to pin 30.
Solder the other end of the cable you've just cut (the OE pump power feed) to relay pin 86 (this is the switch power feed for the relay).
Solder a short length of the 30 amp cable to pin 85 and earth this as close as possible. I think I cut the original earth feed from the pump plug and soldered it here too, then soldered a 30 amp earth cable to the fuel pump plug and earthed that to the same place as the relay.
You need to keep the original fuel pump relay in as, you're still using that feed, to switch the new relay on and off.
It should be noted that you won't get any voltage on the pump side of the relay, unless the fuel pump is priming (the 2 or 3 seconds after you turn the ignition on) or the engine is running. That may sound strange but, the fuel pump only needs to operate at these times so, that's how it works.
So, if you're trying to measure a voltage on the fuel pump side of the relay, without the ecu priming the pump or the engine running, you won't get a reading !
Paul