I would template the Boxster pads onto the Boxster-S get the grinder out and go from there. Start slowly a little bit at a time until they seat in and fit. Perhaps purchasing a set of cheaper pads like Textar compared to DS2000 would be a safer option if things go bad.
I've only done the shims for the Boxster-S currently as I managed to get hold of some race titanium shims for the price of normal shims, and when I brought the calipers their were still loads of material on the brake pads. Once these discs or pads wear out I will be using the Boxster-S pads as I don't like the unsightly look of the 10mm unswept area.