Is it possible to restrict familiar race?

[Nightfox]

Is it possible to limit the races available for familiars through a special or some other bit of coding?

I'm trying (and let me stress trying) to create the Dread Necromancer in Hero Lab. I've gotten most of it functioning, but I want to tighten up some of the features. The class gets the Summon Familiar ability at 7th level, but it is restricted to Imp, Quasit Vargouille or Ghostly Visage. I've added a class special bootstrapped to Arcane Familiar and Improved Familiar, but this leaves the player with the full familiar list to scroll through.

I don't want to go through and change all the animals currently on the list, as i have wizards who like using their crow as a messenger and spy. And from what I've seen so far, the animal companion and arcane familiar/improved familiar mechanics appear to be coded into the program and not into the individual abilities. But I'm hoping one of you bright young minds out there will be able to tell me I'm wrong.

[Aaron]

I think the easiest route for you is to include an eval rule on your Dread Necromancer class which uses the "minion." transition to get to the familiar and then check if it has one of the valid races.

[Nightfox]

Thank you. It seems that you're always the one to come to my rescue. :-)
This gives me an idea of what to do. Not sure how yet, but figuring it out is part of the fun. Now to find some examples....