Assuming they are the ones supplied by Dereks Mini Centre, http://www.dereksmin...sale/4529669452 (which they seem to be as they have appear to have DMC embossed on them), then they should come with both pop rivets and fir tree connectors.
They're essentially held in by friction around the upper damper mounting, and you just need the extra fasteners to stop them flapping around. In the end, I drilled one hole in the bottom outside corner of each flitch panel for a fir tree connector, and then a small hole in the front of the lip of each wheel arch and another on the back of each front panel mounting bracket, I then used small cable ties to connect the front end of the liners at these points.