I don't know if this will help any one.
I acquired this information from one of the mini forums, may even have been this one.
Hope the OP won't mind me copying it here.
Some tips on where to protect our precious cars.
Whilst you are at it here is the diagram of all the cavities that need protecting
http://i1310.photobu...injection-1.jpg
1. There is the forward bulkhead cross member, the floor cross member,
2. the, scuttle corners accessed at the top of the bulkhead near the bonnet hinges,
3 the rear valance closure panels
4. there are 6 coming down from the roof - the door posts which you can do through the hole where the check strap goes
5. the rear subframe, in between/ below where the trumpet sits as this can collect water
6. All of the underneath,
7. battery box, and
8. all the subframe mounting points!
9. Inside the doors especially at the bottom.
Doors - There should be three holes in the bottom of the doors about 1/4" diameter. One in the middle and then one at each end by the curved section Try and drill as close to the radius of the internal door frame flange as possible but don't drill into the door skin. Then paint and then waxoyl (or whatever your choice is) inside the door but make sure your new drain holes are clear.
You can inject Sills through the vents or through the seatbelt holes with an extension probe.You can also stick the tube into the sill from the rear companion bin, take out the liner and you will see the inner sill splits and there is a gap where you can get the lance into.
The vulnerable areas at the front (including the rear of the front wheel arch), at the rear and around the jacking points.
The rear subframe needs protecting all around the radius arm mounting areas and in the trough and webs that run behind the arm.
The A-panels are difficult, being a three layer metal sandwich which is not accessible. Make sure seam sealer is intact where the A-panel joins the inner wing under the car and keep well waxed. Also wax the inner part of the A-panel in the door opening.