I have 6-way power seats that come stock in the TE. They are wrapped with seat shields.
About the straps, the best piece of advice I have to offer is remove the fastex buckles before trying to push the nylon straps down past and through the plastic seat shields. Lay the cover on the seat and see where you need to tuck the straps in. It is a bit of a PITA but not nearly as much of a pain in the ass as removing the shields and/or the seats themselves.
Patience young jedi patience. Take your time they will look better. Hurry to put them in you may mess them up, tear a seam, ect.
In fact I did one seat one night, then I waited until the weekend, to do the other driver and the 2nd row. That was when the idea to use the spatula to ease the neoprene in between the plastic and the seat to tuck them in. Obviously be careful if/when you do it as these are electronically controlled seats.