I did my 560SL idler arm last winter, and the one in my 380SE 2 years ago. Relatively easy job IIRC, about 1 hour, plus connected parts removal/reinstal. I also used a bit of Syl-Glyde on the rubber sleeves, just a thin over-all smear to reduce friction on installation. Most of it will come off anyway as they are pressed/pulled into the tube, a very tight fit.
Use whatever works to get the old sleeves out, including air hammer and long chisel from the top end. The old bolt & nut can be used with washers to pull the new sleeves into the tube.
My steering was making a groaning sound at hard left turning of the wheel, which sounded like it was coming from inside the dash, under the glovebox, which was of course the idler arm sleeves, which had had all the chrome plating rusted away inside and disintegrated rubber.
Not really necessary to grease any of this assembly, but a thin coat on the metal surfaces to prevent rust can't hurt.

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1986 560SL
2002 Toyota Camry
1993 Lexus