Lorry and I installed the steel beam yesterday, using a technique he used for his house extension. The studs are cut 3/4 of the way through just below the base of the beam. The beam is then lifted onto temporary framework aligned with the cuts. Then starting from one end the studs are cut completely (using a Japanese hand saw) and the beam angled into the cut. Once we got to the load bearing portion (in the centre) we added the end posts, bolted them together and placed them on pine skids. The beam position is adjusted with a percussive microadjustment tool maintaining verticality as much as possible. Finally, once all the studs are cut and the posts are in position the posts are bolted to the base plate and the wall can be removed.
The silver at the top is low cost cornicing :)
To determine the effects of live loading on the beam I installed this advanced technology maximum deflection detector. Nature has been kind to me by providing storm winds over the last 24 hours. Despite that, no deflection has been measured.
I adapted a program from Schaum to compute worst case deflections: beam2.py I have a second moment calculator in 2geom, if anyone is interested.