This is the relatively easy part of the EJ conversion.
Lets start with the engine crossmember. On the older EA81 cars you need to slot out the two holes for the engines mounts about 8mm towards the outside of the car on each side. On the EA82 cars you don't need to do this as far as I know. Now that you have done this, the engine will bolt right in, except for the gearbox/transmission.

For the new EJ22 to bolt to your existing gearbox you will either need a 12mm thick adapter plate which will allow the EJ to fit on the EA82 or EA81 gearbox. If you go this way you will also need to either slot out a EA82 flywheel center bolt holes to fit your EJ engine or get a machine shop to fill the holes and re-drill the same EJ pattern to your EA82 flywheel (sorry, I didn't get around to doing this so I have no pictures of the modified flywheel.) If you have a PT4WD 5sp the clutch should bolt to your modified flywheel and slot onto your gearboxes input shaft no worries using the 5sp's thrust/throw out bearing.

The Adapter plate is relatively easy to make on your own. All you need is a sheet of cardboard big enough to trace out the EJ engines bell housing and EA gearbox's bell housing. Approximately a 500mm x 500mm sheet of 12mm or half inch thick aluminum. Along with a jig saw and drill.
To start with the process you need to trace the bell housings. I found this easiest done with very thick cardboard and a hammer. Cut a big bit out of the center (kinda where the flywheel was going to go.) Then punch the two lower mount holes out for it using an EJ22.
Place it over the EJ22 bellhousing, then used a hammer and tap the cardboard around the outside of the engine bellhousing.
Then place it on the EA trans (I used a 4sp for this, but I don't think it matters.) And do the same, but on the inside of the trans bellhousing. Then cut it out and mark the 4 other holes (2 for engine, 2 for trans) with a pencil.
Place this on the plate of alloy and mark it out. Then cut the alloy out with the jig saw and a drill. Using the drill to start off and help making sharp corners and the jig isn't good at that. Drill out the other holes and thread them. Or what would be better is to fit helicoils in the plate for extra strength. Or you can also cut out a slotted shape hole and use two cut off high grade bolts welded together as an offset stud, this would be very strong. If you don't get the top holes exactly right like I didn't then don't worry. Just get the drill and widen the holes till the bolts fit through.

A must look is Numbchux's EA2EJ EJ conversion write up. You can download it from here!