I agree with everything Rob said, I just used a big gun cus I have one, and I don't have a small iron.
In other news, here are some pics of making these coil packs work with legacy ej20g heads/valve covers!!!
First: pop the copper bushing out with a socket and a hammer.
Second: Cut part of the metal part off of the coil pack as shown in the first picture. You can use a hack saw or a zip disk.
Third: You need to cut off the smaller metal mounting hole on the coil pack on only two of the packs. This is because the mounting is different on the passengers side, the big hole doesn't line up with the holes. If you cut these small holes off you can run the mounting bolt along side the coil pack with a washer on it to hold it in. I didn't show a pic of this.
Fourth: Take a dremel or hand file and remove a small amount of material (plastic) where the arrows are pointing in the second picture.
Fifth: Sit back and admire your work.
When I held the packs up before cutting the metal part it looked like a lot of this plastic was going to be in the way, meaning having to cut very deep and expose the internals. Just remove a few mm on each side and corner the edges, test fitting after each small cut and you're good to go. I used a hand file because it really only needed a couple passes to fit, not really worth getting the dremel out, unless you don't have a file.
With the copper bushing out, the hole is big enough that you can use the legacy mounting bolt to secure the coil pack, no need to drill a new hole. Since this bushing is gone though, I suggest using a star washer to ensure good contact with the ground wire.
If anything is unclear let me know and I fix it.