Copy "fasm.lang" to:
/usr/share/gtksourceview-2.0/language-specs
/usr/share/gtksourceview-3.0/language-specs

With "black-woof.xml" do one of the following:
1.Add it as a style to your editor (e.g. gedit).
2.Or copy it to -> $HOME/.gnome2/gedit/styles

Restart all running instances of gedit. Done!

Notes:
You have to use the "Black Woof" style theme to see any highlight.

If you did not like the default color scheme you can change them by editing the "black-woof.xml" file