No, it's not particularly hard. As you're doing a straight plug and play it should be straightforward. Brief guide (there are more in depth ones on here):
Passenger aluminium strip removed (open door, prise off 'side' of glovebox, undo screw underneath). The strip is held in by 4-5 'pins'. They're stiff, so go easy and work your way left to right.
Undo all glove box screws (10 maybe) and remove entirely. You'll have to disconnect the light and USB port if you have it.
Undo the carpet screws and remove any plugs under the glovebox. Remove the plastic trim along the side of the centre console (the hard lighter grey bit - don't move the spongy stuff!). Pull carpet down so you can see behind/the side of the centre console.
Remove stereo, feed cable through from behind, connect and replace stereo. Lay the cable where you want it.
If you want it in the cup holder, you'll have to snap off one of the cup holder flaps or drill a hole somewhere. As it only needs to be big enough for a 3.5mm jack, I guess you can just drill a hole.
The cable should now be loose at the side of the passenger seat. You can simply feed it into the hole you cut (a little tricky depending where you put it). Replace carpet and plastic trim on the side of the centre console, then the glove box, aluminium strip etc. Done. You may want to put a knot in the cable either side of the hole so it doesn't fall through and so it will stop when it's pulled.
All aluminium, it's very soft and prone to scratching/denting.
The spongy stuff around the centre console, very hard to stick back down if it comes unstuck.
Where you drill. The side is obviously fine (it's double skinned around the drinks holder) but I have no idea what electrics etc run underneath.
This is how it looks with the glovebox out and carpet down.