console for JRuby/Sinatra with Tomcat ?

We are using Ruby Sinatra running on JRuby with tomcat as a server.

I saw where it was claimed you could get a console in Sinatra by doing
something like this:
irb -r my_sinatra_app.rb

for me that would be
jruby -S rb my_sinatra_app.rb

but I get this error when I do that as obviously tomcat must
initialize some things:

C:/Tomcat60/webapps/ROOT/WEB-INF/vendor/activerecord-jdbc-
adapter-0.9.2/lib/acti
ve_record/connection_adapters/jdbc_adapter.rb:330:in
`initialize':RuntimeError:
The driver encountered an error: cannot load Java class
com.microsoft.sqlserver.
jdbc.SQLServerDriver