Reversing jaws in a lathe chuck can be tedious. Originally I made two (one for 3jaw, one for 4) small cranks like the one shown in the picture. They worked very well but later I bought a battery-operated screwdriver (great tool!) to use as an impromptu power feed on my Unimat.
A 3/8" socket driver happened to fit the 3jaw but wasn't long enough to get the jaws out of the 4jaw. I sacrificed a 1/4" Allen wrench and made the long reach fitting at the bottom of the picture. Works well.