On boats (submarines), we too had to run the turning gear. But the drive shaft was much shorter and sag wasn't much of an issue. Steam turbine rotor bending was more the concern, due to uneven heating (cold condenser below, and sealing steam applied to the shaft's labyrinth seals). If completely 'cold', like from an IMA or overhaul, we had to run the oil for a day or so just to warm it up to the minimum for jacking (90 F IIRC, for 2190 turbine oil). Then put the turbine/gear on the the 'jack' for four hours before bringing steam into the engine room and applying steam to the shaft seals, or warming the engine.
Lubrication on relatively small turbines (just a couple of ton rotors) is a matter of just having low-pressure oil supply and letting a dry shaft 'ride up' one side of the journal. It quickly pulls a film of oil under the shaft.
Large commercial turbines (on the order of 50 ton) also have 'lift pumps'. Along the with the low-pressure lubricating oil, a 'lift pump' supplies high pressure oil (>100 PSI) to a special port in the lower half of the bearing sleeve. It is enough pressure to force an oil film under the shaft, even when it isn't turning. So prior to first starting the turning gear, the lift pumps are used to 'break free' the shaft from the bearing sleeves. Quite often, once the shaft is turning (with the turning gear), the lift pumps can be secured as the oil film around the shaft is then enough to allow continued turning with the small motor.
daestrom