As above, I've got a twin pick-up sump and oil pump for my engine to help with oil surge etc.

However I can't use my existing pump with the new pipework so how can I check the pump? Also will I need to prime it or just turn it over without the plugs connected?

I'm not exactly sure what you're asking but to check an oil pump, you take it to bits, check it for scoring and check the clearances with a set of feeler gauges.

When reassembling give the pump rotor a liberal coating of petroleum jelly to help it it self-prime.

you mean in the take off's/pick-ups? I take it that it helps draw the oil in to start pumping?

Just the rotor and gears inside the pump. Use Vaseline rather than grease because the Vaseline will disappear into the oil as the engine warms up for the first time, grease won't because grease contains solids.