OK, so, stage 1 choices. A success on any of these will allow you breathing space to get up the stairs.

1. Makeshift barricade. There's no time or space to really stack stuff up, but you could hurl something large and heavy into the doorway and profit from the temporary obstruction (maybe knock an Iron Company guy down even). Straight Strength test.
2. Superior fightin' skills. A prone Iron Company man in the doorway is also, to all effects and purposes, a makeshift barricade - and with others behind pressing to get in, they have less freedom to move than they might like. A successful Manoeuvre test can push one of your current attackers back into his mates such that he either falls or tangles them up long enough for Sieghard to make a break for it.
3. Scary Sieghard. Sieghard has shown he's a very dangerous fighter and the guys in the doorway are having to fight him without the support of their pikes or their friends. If he can convince them that being at the head of the chase isn't worth dying for he may get a moment to break off - after all, as far as they know, he's trapped in the mill. Of course they are hardened soldiers so this will be difficult - let's say an [u]Intimidate at -20[/url].