I agree, once you have the ladderstand racheted to the tree, climb the ladderstand and install the lifeline.
That's what I do. Putting one up and taking one down is so much easier and safer with 2 men for sure. This hits home because I took down an old ladder stand this past weekend by myself. Even though the stand was ratcheted tight and solid against the tree and tied off at the brace, coming down after I took off the life line and released the ratchet straps from the top was a little bit scary.
Dr. B