I just keep it simple. I've a small crow bar, I jamb in on bolt head. It really takes very little to hold (keep from spinning). Sometimes nothing is needed.
Even if you don't mark or measure the T-bar, which you should. Look close, you'll see they have marks and or teeth, to help orient. Personally, I like to mark bars and threads or count of it's adjuster bolt. I then get back as near post position on assembly, while on jack-stands. I just find...
Just torque, after assembly once on all 4 tires back the ground.
Again @nissanh is giving the pre disassembly measuring method, to set bushing in neutral stance. Which is to avoid the PITA of torquing once back on ground.
The goal is to have rubber of bushing in neutral (no rotational pressure...
Quite frankly, I'd not considered serrations on nuts/bolt. We have few nuts in the 100 series with serration (I don't recall if control arms have them.) One example would be fan clutch to fan brackets' 4 nuts have a directional serration. We can only torque nut.
Long Bolts Are Being Used – When...
Either measure as OP and you've done, and or torque after all done and laden.
Alignment afterwards, is good idea. Which you can then have nuts/bolts re-torqued, once on rack (drive on rack). To that end, I've circles nuts/bolts and written torque on parts. Then had alignment tech torque.
You...
He's measured the position of LCA, while it's bushings were laden (weight on tires, vehicle level on ground). Then set LCA back to those measurements, for final torque. This "close enough method", is preferred by "some". Since getting swing with long arm of torque wrench, so difficult while...