You may have already came across this but this is the only manual I found in my searches of the web.
Its basic stuff but may help.
http://www.ohlins.com/Motorcycle/Pro...0/Default.aspx
Click on:
MX/Enduro/Off-Road shock absorbers
Trial/Off-Road shock absorbers
They are PDF files.
I do know that you need a special needle to insert to fill with gas.
I spoke with a friend who does alot of suspension work and he drills and taps for a schrader valve so it makes adding the gas more universial.