I prefer Intel-style, but a lot of code snippets on the web are AT&T style. So, is there something to convert (I don't want to hand-convert) automatically? Is it possible to add this functionality as part of FASM, or perhaps as a separate program that comes with FASM or can be downloaded from FASM website? Or maybe I should write one myself.

I don't think that there's a program that does such conversion...

But it doesn't work for FASM. Maybe I will make one for FASM. I will make it for DOS, probably not in FASM (I'm not good at parser and these things like that.) but in an HLL...