I think, that you can't really because the side strip is on full piece. I think that what you have to do is to actually cut into the VTR/S arches so that your bump strips run underneath, cut your bump strips so that they fit upto the new arches or fit VTR bumps stips.
You can get a bodyshop to get it done. But it wont fit with the standard 1.1 rear bumper so you would need a VTR one or get them cut down.
You can buy arch extensions for your 1.1 which make it look a little bit wider than it already is.
http://i8.ebayimg.com/04/i/04/95/7c/ec_1_b.JPG