What's the best way to get them in the correct position on the shoe.

There's no perfect setup, there are too many variables. Basically, fit the cleat approximately in the area around the ball of the foot, ride and tweak.

Important edit: Stop riding and adjust if any sign of knee discomfort.

As above,Get the cleat so ball of foot is over axle of pedal. Side to side so heel not striking chain stays. But may need to tweak for comfort.
However, you'll get plenty of practice as the cleats are made of cheese.

Sit on a table so your feet are off the ground and the same distance apart as your pedals.
Look down at the angle that your feet rest at.
Set your cleats to match it.

That's fine for angle Keefy, it's getting it too far forward or back that is bugging me.

Are the eggy premium cleats worth the extra dosh?

I've set mine slightly behind the ball of the foot. Too far forward and it felt like I was pedalling with the toes - and it was more awkward to spin the cranks. Too far back and I kept getting cramp in the arch of the foot.

Happy with standard so not used the premium.

I set mine up the same as sprokitt - slightly behind the ball of my feet.
The only way to do it is go for a ride and give it a tweak.

Are harder wearing premium cleats a good idea?
I thought they were made of (relatively) soft brass so they wore instead of the pedals.

Thanks gents. I will set them up and tweak on tomorrows ride.