Fire resistant paint will help a little, but I dont think it will do much.
Put a smoke detector over it, I still think that your over reacting if you don't have an ansil system installed in your kitchen, the number one source of home fires.
If you really want to do it well, I might go this rout. The way to fort fire is to remove any on of the key elements, fuel, heat/fire, and oxygen.
So build an airtight box, or at least one that is only gas permeable on top. You might get an old steel fridge and cut a hole in the top. Then allow CO2 gas to slowly seep in at a slow and constant rate. Presto, you have remove O2 while not disturbing anybody other than your insurance adjuster, who will have no recourse but to give you some sort of discount.
Another option would be to get a mettle cabinet and surround it with brick. Kiln bricks would be the best, as they are light and have the best insulating characters.
If money is no object, get a Halon system. Just make sure nobody is around when it goes off.
I would be worried about frying the computer if your attic gets hot, but thats me. Also a turn key solution would be to buy a double walled steel reagent closet. Some chem. labs use them.
Good luck, and I hope you system is flame free.