A weekend
I did it all four in one weekend, but only after the f*****g parts guys got the inserts the wrong size twice, I finally worked out how to get the f*****g gland nuts off....... preparation is the key.
P.S: Dont be afraid of damaging the gland nut, because you'll get a new one with the shock. Unless youve got the mother of all gigantic socket sets and an air powerd rattle gun, you'll have to use something like a pipe wrench (Stillson wrench) to get that big momma off.
And yeah, like mizhele said, put motor oil in. The origional factory shocks were completely different to modern ones, and worked via a damper pushing through oil that filled the entire case. If you put the modern inserts in, you will have an air gap between the insert and the outer case, which acts as an insulator and keeps heat in. Oil will conduct it out.
A word from the wise - do the gland nut back up as tight as possible. My friend didn't - and it came off, allowing the sping to fire the whole strut off the car!!!!!!