The installation is reasonably easy. You should estimate about 3-4 hours to do it, taking your time with the trim removal and laying out the Dynamat.
If using other subs I'd be sure to check their minimum power requirement. The JL 10W1V2-8 I used is specified for 60W minimum. The stock amp won't drive a sub with too high of a power requirement.
Overview: remove the D-pillar covers and the B&O speaker grills, remove Torx screws, remove rear deck cover, swap the sub, lay some Dynamat (optional, but recommended), wire it in, reinstall trim.