Open the glovebox, notice the retention tab on the passenger side, circled here.  My glovebox is currently as full as it can get and still close, yet I don't have to remove any of that crap to replace the filter.

Grab the passenger side of the glovebox, and pull it towards the driver's side until the retention tab (seen above my thumb) is free of the dash and the glovebox drops towards you a bit.

Do the same on the driver's side for the other retention tab, and the glovebox will drop a bit more...

Now all that is keeping it from dumping its' contents on the floor is the damper, seen here.

Simply hold the glovebox with one hand, and stick your other hand between the damper and glovebox and push the damper off of the pin.

At this point, only the hinges hold it on.  Pull it away from the dash, towards you.  The direction you pull should parallel the main flat face of the glovebox...

because as you can see here, the hinges are cast with the release areas so that pulling parallel to the main face releases it.  Set the glovebox on the driver's seat.

Circled at bottom are the hinge pins cast into the dash.  The release tabs for the cabin filter tray are circled at top.

Push each tab towards the middle of the tray to release the tray...

...and pull it out SLOWLY.  It may be covered in leaves and who knows what else, and you want that stuff staying on the tray for removal, not dropping into the ducts.  It probably wouldn't hurt to vacuum out the duct after removing the filter tray, if you have fittings that will fit in there.

This is an aftermarket replacement with many more pleats.  It is relatively clean as I installed it a couple of months ago.  Normally, you will find leaves and stuff.  The stock filter has no frame on it, it is a formed sheet, you just pull it out and work a new one back in (or wash the old one and reuse), making sure the edges fit under the tabs in the tray (there are "top tabs", visible here, and "bottom tabs" inside the tray - the bottom tabs capture the edge of the stock filter).

It's hard to see, but on the right side of the tray, it says UP with an arrow, so it's pretty hard to put in backwards.

Place the glovebox onto the hinge pins.  You don't need to hold the glovebox as low as I did, as it might dump some of its' contents, I just held it this low to get a pic of the hinge.

Push the glovebox back in until the driver's side retention tab snaps back behind the dash frame, but NOT the passenger side, as seen here.

This is the first part of the entire job that can't be done one-handed - until now, I've been doing it all with a camera in my right hand the entire time.  You have to push the top of the damper towards the front of the car so it pivots the bottom down into view...

...as shown here.  Grab the bottom of the damper with your other hand and snap it over the glovebox pin.  Then push the glovebox until the passenger side retention pin snaps behind the dash frame, and close the glovebox.