An abbreviated dial (ie. system speed call) cannot be a destination for a Call Reroute in form 19 of the SX-200 (Years ago you could, but in the ICP you cannot)...
To do this would require using a phantom extension and call forwarding it to 911, then set the Form 19 Attendant position for that tenant to the phantom extension number.
Honestly, I would check on the legality of this... having a hotline to 911 is seriously frowned upon by most emergency dispatch centers. A local hotel was fined recently a fair amount because of this actually... they had a pool phone that hotlined to 911, and the jack got corroded and shorted out and sent hundreds of calls to 911 over a weekend. The end result was a phone with a restriction to only be able to dial internal and 911 and a big sign, and they had to write a fat check.