How do I access Bar information at the current right-hand-side of chart window?

I need to access the Bar information at the current right-hand-side of chart window? I am trying to build an indicator that works off the current right-hand-side price bar for manual back-testing instead of the last price bar in the series. In effect, I would like a dynamically changing indicator based on what price information is being viewed in the window at a given point in time. Does anyone know if this possible? Thanks in advance.

Cheers,
Enforcer