A guide hasn't been done before i don't think, so here goes!
What you will need:
4x Headrest anchors.
1x Tape measure.
1x Some kind of marker/scriber.
1x Small Metal drill bit (Pilot hole).
1x 20mm Metal drill bit.
2x Metal files - One completely circular and small and one rounded..
1x Decent drill *Cough* Makita *Cough*.
1x Knife or scissors.
And some elbow grease.
Get your headrests and anchors from the scrappy.
To take the anchors out all you need is a rod of some sort and push it into the square hole on the top of the anchor and then it should just slide out. I didn't have a rod so i did it the hard way and pretty much destroyed the seat.
Put your headrest in the place you want and mark out both poles on the back of the seat, do the same for the other side.
Next you will need to take the seat sponge off, this is done by unscrewing the plastic screws on the back of the seat and then it shall wiggle off - Be careful with the screws because they aren't very strong and you can ruin the head easily.
Now that is done you can get down to marking where the holes should go.
There is a hollow ledge on the top of the seat with a flat bit and a sloped bit on the back. I marked my holes in the centre between the edge and the sloped bit and in the position where the headrest should go. It's probably best to get the headrest and mark up to that as then you know it will fit.
Next drill a pilot hole for the 20mm bit to go in.
Then proceed to drill with the 20mm bit. (I used a flat wood drill bit as the metal bits are extremely expensive and mine only cost 75p from in-excess and it didn't actually blunt it.)
Drill 2 more pilot holes to the left and right of the hole as the anchors are'nt round.
Next you need to file down the big hole with the rounded file to make it smooth and a bit bigger. And then use the completely round file to file through to the pilot holes and make it look like a little face. (Trust me the pilot holes do make it a alot easier!)
Depending on the position of the headrest, another big hole may need to be drilled underneath if the hollow beam isn't that big.
Now try the anchor and see if it fits... if it does.. congratulate yourself with a cup of tea.
Now you need to cut the seat sponge, rest it ontop of the seat back and cut right on top of the sponge in line with the anchor holes.
(It's best to cut a small hole and then force an anchor through it as this is neater and you won't have to repair it if you make it too big and it also makes the hole through the foam.)
Now is the easy bit. Put the anchors in the sponges and slot them in the holes, and then put the sponge screws through the holes and do up the plastic screws... easy as that. You may need to get a mallet and bang the anchors down a bit.
I will post more pics up when i do the other seat, just i didn't decide to do a guide until the pics started lol
She's still alive! -23/02/2017