I use this technique somewhat, but not always, and more commonly I fret the 4th and 5th strings of a normal E chord with the middle finger, which is easier, and, I think, more essential.
A couple things. Don't worry about getting it to sound perfect, just keep playing while using it, buzzes and all. Eventually you will develop callus at the "corners" of your finger tip that will work much better than the groove down the middle you have now. One thing that helps is using a guitar with a narrower neck for a while. Again, don't worry about sounding good, just play the songs on the narrow guitar. Just listen without trying to stop and "correct" your finger placement. Sometimes if you can manage to get your brain out of the equation and just play and listen, your ears will communicate directly with your fingers and things will just get better. Playing while singing really helps accomplish this.
Technique-wise it's good to fret with the tip of your finger as if you are fretting one string. Don't be tempted to slightly flatten your finger to get a little mini barre, just keep putting the tip right between the strings. eventually, as the callus begins to develop you will start to get a sense of gathering the two strings, especially if the right hand picking goes from one to the next, and around the same time you'll have developed the two groove callus and, well, there you are. Move back to your wide neck fingerpicking guitar and play away.
Hope that helps.
My problem right now is practicing enough to keep that two groove callus.
Wax
