lucien, you'll find MOST momo knobs actually use screw with an allen key end that you tighten so it holds against the stick.
You should consider one like this:
http://www.nismo-webdirect.jp/webdirect/im...013_shohin2.jpg
Unfortunately it isn't listed in Dave's group buy, but Japan Parts do have it:
http://www.japanparts.com/shop/shop.cgi?mo...ype_third=NISMO
listed @ $180AU (I'm waiting on a response from them if it includes shipping). Nissan Australia can get you it for $300!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Basically, you screw down the bit thats in the bottom right corner of the first picture, then you put the knob on, then you screw the bit in the top right corner of the picture.
It's titanium, and it looks awesome.
Hopefully I'll be getting one in the next two months, so I'll let you know how it goes if you haven't got yours yet.
Jason.
edit: The Japan Parts picture does NOT do it justice as they've scanned it in from the Nismo catalogue