Hmm, I suspect that such actions were well outside Dan's original intentions. My own thoughts are:
Mounted troops cannot enter buildings, let's not get into dismounting/remounting and horse holders.
No more than 6 figures may enter, so 12 man units count as half strength. You may prefer to limit it to 3, probably more realistic so every unit is at half strength.
Rules for fighting in rough terrain apply. Your heroic knight can get his brains bashed in by a serving wench who is hiding behind a door. I wouldn't even give foot knights the benefits of the Ferocious rule.
No missile fire.
TBH, I'd look at using an entirely different set of rules that focus on one to one combats inside buildings.