I just did this with some friends of mine. There is actually 3 different tension bars and each of them have three settings on each side of the bar.
If you get get a belt or chain come along or ratching belt assembly you should be able to do it fairly easy.
I drove onto the street
placed vehicle in park with safety brake engaged
attached chain to wooden street light and atteched other end to tension rod on the firewall side of the thesion bar,
If you are standing at rear of vehicle looking at the firewall the two hinge bar face each other and are adjustable by removing the steel retainer stud which looks like a large nail. The majority of them I have seen have the stud in the center position, If you readjust the stud towards the firewall the tension is lessened and if you move the stud towards the rear or trunk then the tension increases.
Once tightening device or come along is properly secured start ratchating the come along or device to slowly pull the tension towards the rear, as you do this the stud or oversize nail will become loose and simply pull outwards.
Apply enough tension slowly to pull the bar rearwards to enable the pin to be placed in the rear hole or the hole closest to the trunk
Slowly let off tension or ratcheting device or comealong and do the same for the other side of the trunk hinge.
I cannot stress enough that these bars are tension bars or torsion bars, they get their spring effect by the more the pressure on them to move the trunk lid upwards. Use extreme caution when dealing with them otherwise you will kiss you back window good bye and maybe even some body parts if they become loose.
With proper care and respect for the sheer force involved it really was not that hard.
Actually "watts" did the work while I supervised and held the chain high enough so we had a direct unobstructed path downwards to put tension from the ratcheting come along.
Tim