I've done it a couple of times, using a slight variation of the method Sheldon Brown suggests. I put the frame on a workbench, with rear stays protruding over the edge, then the lever facing forward. I also keep the string in place to be able to monitor progress as I work. Don't want to overshoot and have to bend back.

Different frames have very different amounts of spring back, so one really has to check the result frequently. And preferably have some sort of stroke gauge to provide some indication of how much bend you should be using.

So far, no issues. Some have reported popping off brake bridges.