This is a simple modification to the LUA script included with the FloatingX HUD program. It adds an ammunition counter for the Alien Weapon. In keeping with the spirit of the FloatingX HUD, the ammo count jitters and flickers around with the static displayed in the HUD when using the Alien Weapon.
Download the FloatingX HUD from this site, back up the FloatingX.lua file inside, and replace it with this one to install.
Simple code change to the FloatingX.lua file tested in Marathon 2 using latest Aleph One build.