I have put a set of forks into a new frame with its headset, and put everything back in the right order, but have limited tools over here (and short of a couple of headset spacers). How do you get the split ring on so it stays tight and where you want it? It slips up all the time, but obviously it is possible to get it to seat properly as I had use some reasonable force to get the old forks out. Will it be OK to get the extra spacers and use the star nut/top cap to push it all together when I tighten it all up?

Never had this problem before.

Oh and the Kona site says it is "Headset TH w/Big Nut" and I can't remember what it actually is on the bike as that means nothing to me

Off back to chew straw on the green now…

you need to compress the whole lot with the star nut to get it to crimp together.
assemble it, headset, spacers, stem and all. and you SHOULD have about 6mm space above the topcap before the steerer tube starts (to allow for compression)

tighten it all up with the top cap (this is with the stem LOOSE)
tighten it so the headset becomes "a bit tight/stiff" then undo it 1/4 turn.
nip up the stem.
it SHOULD feel about right, and with the front brake on, the headset shouldnt rattle.
once youve got it set up ok, undo the top cap to take the tension off it, and then do it back up again tight enough so it doesnt rattle or come loose, it shouldnt be under tension really once the stems done up.

You shouldn't really need any tools other than allen keys.

The split ring will tighten iteself as your load it with the top cap.

eg put everything together with bolts loose, tighten top cap bolt until the play has just gone (front brake on, rock bike forward and backwards) and then tighten the stem bolts to clamp it all in place.

Maybe asking the obvious but you are leaving the stem clamp bolts loose when you're tightening the top cap bolt aren't you (you'd be amazed how many people don't!)

OK that was what I thought and hoped, I just don't have the spacers at the moment. Thought I had managed it before, but always had plenty of spacers knocking about and had metal split rings which seem to grip the steerer better.

Flatmate's bike might become a donor bike later

You need to get it so that when all the bits are together, the top of the steerer tube is about 5mm lower than the top of the stem (or the highest spacer if you have them on top. If you don't then the top cap is just tightening against the steerer (instead of pushing down on the stem) and doing nothing useful.

Have a look here, it explains everything in better detail than I can
http://parktool.com/repair/byregion.asp?catid=10&imageField2.x=34&imageField2.y=9