Tether Straps and affixing to your car questions

Has anyone done this? How difficult is it to rearrange the car seat once the tether is in place? Also, the tether is only to be used in the forward facing position, correct? I am about to purchase a Costco Alpha Omega and it comes with a tether strap. I purchased the part (a bolt looking thing) from my dealership's parts department ($3). They told me it would take about an hour and cost one hour's worth of labor at $80.

I thought I read somewhere this is done free at dealerships?

It's definately worth the $80 but I want to see if any of you know about it being done for free?

Thanks for any info.