I did a "ghetto" install of mine on my Touring (I wanted the crash bars... and they've already paid for themselves, dropped the bike at a standstill and it stopped at a 45 degree angle instead of smashing to the ground).
Basically, I took a long threaded rod (an unthreaded metal rod of the right diameter would have been better but it was what I had to hand) and used that to gently tap out the long bolt up top on the Touring and the bar took over temporarily and supported the engine in place, so it couldn't sag and misalign the bolt holes. Then I just added the engine bars and tapped the threaded rod out gently with the original bolt. I didn't have a lift at the time and the ghetto method worked.
On the Touring, the crash bars are just bolted on to the bike on the sides at the bottom, the only through bolt involved is the long bolt in the upper part of the engine up front. Not sure how it's secured on the Roadster.
But ideally you want a jack to support the engine and a stand for the bike, of course. If you pull a frame bolt and the engine sags and misaligns the holes, you won't be lifting it by hand...