At SATURN 2009 Pia Stoll from ABB described the use of a tool to support evaluating a software architecture for certain aspects of usability. The abstract of her talk is here. In the ABB experience, the architect used the tool for 6 hours and estimated it saved him 5 weeks of effort.
A version of this tool is now available for dowload. You can find it at here.
– Len Bass, SEI