The way bloom works is easy:
- Make a "copy" of the rendered image
- Decrease brightness; Black parts won't be "bloomed", the brighter it is the more visible the bloom will be at the end
- Add blur to the image
- Mix the bloom image with the original image

There are some important steps missing such as downsampling, but in theory that's all.

And regarding the shader:
I'll do this tomorrow (and hopefully finish it tomorrow, too).

I thought about using the entity's red, green and blue values as glow color and using the skin's alpha channel as glow-intensity-map.

Maybe I'll also take some of my post-process shaders and combine them for you.
Probably a nice bloom shader and a zoom-blur effect ( looks nice for this kind of games )