Now, the list of available monsters is set in MonsterContractType.cs.

Just add new lines like this :
new MonsterContractType (typeof(Scorpion), "Scorpions", 10),

where you set 
- the type
- the string name you want to be displayed in gumps and items
- the difficulty to drop that type, smaller it is, more often it will be dropped

Enjoy as the original ;o)

