If you look in the MakePet function in spells.cpp I setup a way for the mage epic to cast its spells, its under a switch, if you look above that function, thats where all the pets are you can set a "type" and define it in MakePet, for example:
MakePet(((int)(3 + ((tmp-2) * 3.5) + (rand()%3))), 0, 75, 2, 0, 4 + (((float)(tmp - 2) / 14) * 3),

; //Notice the 8 at the end? thats the type
then under the ::MakePet function in the switch add
case 8: //Setup whatever for that special pet
{
//bleh
break;
}
Just an idea for you, sorry if its not clear enough