They have a threaded in seal head. The late model ones were peene/crimped at the factory so that when you went to unscrew them it basically destroyed the head and body. They were made to be throw aways by then. If you are lucky enough to not have this then yes you can get them apart no worries. No one sells 'kits' for them. They have an odd shaft size. I have one that is about 11.7 and one 10.7 from memory. Or it might be 10.7 and 9.7 i cant remember off the top of my head. They are known as Koni 23X shocks. Dont bother ringing Ikon, they have nothing for them and no information apart from maybe a bump stop thats all.
These are some of the dimensions i got from mine
KONI 23X Remote reservoir shock absorber o-rings
Reservoir floating piston – Imperial 323 – 32.69 x 5.33 – Viton
Reservoir end cap - Imperial 127- 36.17 x 2.62 – NBR 70
Seal head – Imperial 122 - 28.24 x 2.62 - NBR 70
Shaft piston – Imperial 024 – 28.30 x 1.78 – Viton (this is under the piston ring)
Piston ring – 1 x 5.00 x 100 (the actual white PTFE piston ring)
There were 2 size heim joints used that i know of. 1 is off the shelf and pretty common SKF/IKO/ASK type brand and the other is 25mm that is not very common and only available from specialist bike suspension rebuilders/parts suppliers.
Most people convert them to 12mm shaft because of the odd size shaft and either make whole new seal heads or convert the stock ones so that they use common seals and DU bushes.
Sean at SOS suspension has rebuilt these before for people and is familiarwith them so i would try him.
I have a bit of info on them like original owners/fitting info , cut away drawings, part numbers for the different fitments etc but i am not sure if i got access to it anymore as it was on a hard drive that packed up and wont power up properly but theres a chance its still on the computer.