Just went thru this not too long ago, might not be the best way to do it but....
Tools needed: 2 C-clamps and 2 flat washers about 1" in diameter
Place the washers so around 1/4" of the washer covers where the recoil spring sits, you also want each washers 180 degrees away from the other. Clamp the washers down with the c-clamps so they dont move. Hook the recoil spring into the recoil cover and then slowly wind the spring back in. The washers are there to keep the spring from popping back out while youre winding it in. Might take a couple trys to get it started but once you have a few coils in, it should go pretty easy
WEAR GLOVES AND SAFETY GOGGLES