>Has anyone configured a COM+ component to run as an NT Service? If so, is the construction of the component any different than a component not running as an NT Service?

Nativelly, you can't make NT Service components with VB6 unless you use third party tools.
I know two: a free one from Microsoft that is unsupported and a more robust one from Desaware.
Link to free tool: http://www.gvbm.org/Document/2000Septembre/ServiceNT_VB.zip
Link to Desaware: www.desaware.com

BTW, you can't have a NT Service component in COM+ (Transaction Server).