helping in edit md3.cfg ?

[Mr.Floppy]

The easiest way to add the muzzleflash tag is importing an 'original' model and using its tag while deleting the model itself again. This way you can also adjust the positioning and angle easily, too.

You certainly wil have to change the mdl_tag values to make it fit your particular model, which should by like tag_muzzle X Y Z, I think.