quicky re Wadia input card 518se

Gents, quick question - I've searched all over with no luck so had to start a thread -
I'm ready to plump for a Wadia 581se but suspect that I may need the "i" input card in the future... Does anybody know whether it's possible to buy one of these myself and fit it or will the machine have to go back to a dealer? I'm competent enought with these things - building PC's etc. - and would like to know if this would be a similar job. If it's tough I'm probably just better to hang on for a 581i-SE.
Appreciate any advice, thanks!
Oscar23.