I found some M5/M6 size WELL NUTS on EBAY that are made of neoprene that fit in the original holes and are usually used by Ducati Motors, The idea behind the WELL NUTS is that you can push them into a 9.6mm hole (the fitting kit hole in the is200 body is 10mmx15mm) so these are just slightly smaller than the original fittings by the look of it?
When you fix the skirts in place front and rear with the screws the skirt will stay in place and allows you to fit the WELL NUTS you push them through the holes in the skirt and into the holes already in the bodywork (you have to cut the underseal to show the factory holes) then insert the bolt/washer that comes with the well nuts and when you tighten them up they pull in and collapse from inside the body to hold the skirt nice and tight and also seals the hole being rubber, and if you ever want to remove the skirt in the future you just undo the bolt and the well nut will come out and can be used again (not like the originals)
Heres the info on them..

Simple to install
Place 'Well-Nut' insert all the way into the pre-drilled hole (9.6mm) until the flange is firmly against the mounting surface.
Pass the machine screw through the part to be fastened and tighten until snug
'Well Nut', a flanged neoprene bushing with a captive brass nut, is designed to provide a shock and vibration resistant fixing for engineering structures. This demountable blind screw anchor is suitable for applications of many kinds in many conditions, in materials from thin gauge metals to plastic sheet up to 16.5mm thick; a high rate of radial expansion even allows use in blind holes in solid materials.
Benefits:
Access needed to only one side of the workpiece
Used with standard metric machine screws
Fastens in blind, burr-free holes
Can be used in closed end holes
Will not mar prefinished surfaces
Helps seal out ambient moisture
Absorbs noise
Electrically isolating
Dampens vibration and shock
Helps prevent galvanic corrosion
Ideal for metal-to-plastic and other mixed material assemblies
Resistant to ozone and weathering in outdoor conditions
Suitable for marine applications
Removable and reusable
Not sure if the info will be of any use to anyone? but may make it easier to fit the side skirts if your stuck for fitting ideas and also means you dont have to screw through your bodywork
