I have got k&n GenII on my car so it is a lot easier. Not haveing to remove the standard airbox. Also when i do a change i like to put in an engine flush. It tells you to idle the engine for 15 mins at 2000rpm, This seems like for ever and i dont like doing it. So i put the flush in when i am driving the car and drive slowly for 10 mins then im ready.
You need to remove the standard air box. This is the worst part it is tight and you will no doubt have sore hands and cut fingers, Think it took me about an hour to prise it out of there. Im sure you have to also remove the ECU which is on front of the airbox this is on with 4 torx screws the bottom one is hard to get to.
Once this is removed get the car jacked up and remove the sump nut, Remember the oil mabe still hot. I use an old basin to drain the oil into. Once the oil stops i can then lower the car down till its level to get all the oil out.
While waiting on the oil draining you can remove the oil filter, You need a big spanner here think its 36mm. Once off replace filter with new one, Give it a firm push in and replace the rubber filter seal. Put a small amount of clean oil around rubber seal to stop the rubber from twisting when you put the filter back on.
Once all the oil has drained you can replace the sump nut. Some people put on a new washer i dont. Now top her up.