Swap MSagents using keywords.

[WillNight]

Exactly how would I go about swapping out msagent characters by talking to hal. Let's say:
User: Let me speak to Melissa.
Hal: Ok, let me get Melissa for you.
Now Hal will load the new msagent in place of the current agent, and change the HalName and brain optionally.

If anyone could help, I would appreciate it.