Leonardo Landi:
I tried several methods too, but in the end I found the "Adam Block's way" to be the more controllable.
first, you need to subtract the continuum in some way (seti astro continuum subtraction, pixelmath, photometric continuum subtraction...)
The second step is to make the Ha the colour you want. You can use Pixelmath but the easiest way is to use NB color mapper. Do not saturate too much the Ha at this point. You will certainly do this later.
The third step is to make the background black. Use HT or curves and clip as much as you can leaving only the interesting signal.
Then use ImageBlend to do the magic. RGB image on top, HA as blend layer and "screen" blending method.
I really love to shoot HaRGB and all my pictures are made this way.
Hope you like it!
I've found that depending on the image sometimes screen works better and sometimes overlay works better. I usually try both and see which result I prefer. In tricky cases I take both layers into photoshop and blend them there.
