Hello Ghost_Fang,
DP_GFX_QUAKE3MODELTAGS is exactly what I would do, too.
"setattachment" is your best friend i guess

I think SUPA wrote a small tutorial here in the inside3d forum how to exactly use "setattachment".
Pleased search for it if necessary.
Inside the monster spawn function you will have a small random function that selects the head.
Then use "setattachment" to glue them together.
Good luck.
Seven