I am sure you can just remove the linkage and put it back when you're done, without disturbing any of the settings to the air/fuel mixture and other injection settings. Just don't change the length of any of the rods.
If you have to jack up the engine to remove the cover then I would guess your engine and/or transmission mounts are worn. I can get the cover off without jacking up anything, no problem. I put in new mounts.
It is a good idea to replace the three washers underneath the bolts that keep the valve cover in place, if you have oil seepage there. Also, I understand that the intricate, big rubber gasket does not need to be replaced unless it has become hard/brittle. If it's supple, there should be no need to replace it.
Final tip (courtesy of Joe Alexander's son Jamie who told me this last summer when I was in Ohio): don't overtighten the 3 nuts upon re-assembly. If you do, this will distort the support brackets that the bolts go into, possibly to the point where the bracket(s) touch (actually grind) the camshaft ("now where is that noise coming from?")!
Cees Klumper in Amsterdam
'69 white 280 SL automatic