I may have the wrong gun in mind, but does the Model L have a little lever on the right side of the frame opposite the saftey lever?
If so, that lever is on a plate that contains part of the slide rail. When it is turned, the slide can be removed by pulling up and back.
If this is the case, turn the lever until there is a gap in the rail. Then put the recoil spring on the guide and put the larger end of the spring guide into the hole in the frame. (The guide also serves to tension the safety.) Drop the open part of the slide over the end of the barrel, insert the front of the recoil spring and guide into the hole in the slide and pull back the slide until the breech block part of the slide (the part with the firing pin) clears the end of the barrel, then push the slide down and move it a little until you can feel it set down into place. Turn the right side latch to lock it. It is very simple and easy as pie once you know the score.
Jim