well i installed a set of stainless lines on my car however the engine and transmission were out of the car as one unit at the time of install.
Based from what i saw you would have to at the very least have the radiator out so you could slide in the lines from the front end.
i need to look at my undercarriage again i think it does go inside of the passenger motor mount, depending on clearance you may need to remove that motor mount and jack the engine up.
i know you will have a pickle of a time getting the stainless lines to go into the transmission couplers correctly, stainless will not give at all and you have to make sure its aligned or it will cross thread, and you will need to tighten the connections down beyond reason to stop leaks.
i have stainless on every line on my car, if i did it again i would not have used stainless.