Check out the performance monitoring sampleperformance monitoring sample, It contains a nice console that you can easily use. (Just take the console class and manager). It contains some nice code to register commands, have arguments, and alota lot of stuff.
http://create.msdn.com/en-US/education/catalog/sample/performance_sample
Also, Thisthis may be abita bit overkill, Butbut I personally use Neoforce ControlsNeoforce Controls, Whichwhich has a nice UI library, including a Consoleconsole.