I have been in your exact shoes, being the developer in a QA group. What we did was this:

1. Create an event handler
2. Each event is associated with a function (or some object/method pair ... your choice)
3. The event handler chews through a list of pending events
4. A given event can modify the list of pending events (so, LoadCommands would "Do The Right Thing")
5. Create a starting event (like LoadCommands <filename>, or somesuch)

You might want to look at POE. We rolled our own, but that was almost 4 years ago, when POE was still in infancy. The other nice thing about doing event handlers is that simple scripting commands (SET, JZ, JNZ, etc) are very simple to implement. Once you have JZ and JNZ, you have (almost) all of your basic logic-flow (if, while, for, etc) implementable in those terms. (They're actually implemented in those terms in most ASM flavors.)