The ej22 is a much simpler swap, you use the same engine adaptor as with the EJ20T. The ej22 requires no major clearancing in the engine bay and you don't need to move the engine/tranny ahead to get it to fit inside the engine bay.
The ej22 puts out around 140hp depending on the year and the ej20t puts out between 200-230 (USDM stock) depending on the year. A friend of mine has the ej22 in a 69 beetle and loves it, still has an enormous amount of power and the tranny doesn't cost a fortune, I've put an ej22 in my 69 van and it works amazing, i've put 35000 miles on it since and not even a hiccup. I'm currently putting an ej20t into my beetle and there is a considerable amount more work to do just to get it to fit. It all depends what you want.
As for whats involved, you need to buy an adaptor plate and flywheel (or get yours modified), you need a transaxle that wil take the torque, find a rad and make some mounts/airducting/piping to move coolant/ fuel tank modifications to move more fuel. If its an ej20 you'll need to get air to the intercooler or use an air-to-water intercooler and mount a coolant pump.
A couple sites:
www.vwrx.com
volks swap
www.naisoc.com for subaru info.
Hope that helps
Mike