Lowering a 87 GPX RII

Hey guys, well heres the deal my missus has the bike bug now and wants her own bike, so im going to give her my GPX and save and get something bigger for myself, but there is one problem she cant touch the ground properly on the GPX and i heard there is alot of people on here who know alot about the GPX's, How do i go about lowering the suspension on the bike is it hard job or can i do it myself in my garage?
Any help will be greatly apreciated
Cheers Greg
Any help will be greatly apreciated

Cheers Greg