bind data access page textbox controlsource property at run time

Is it possible to bind a data access page textbox controlsource property at

run time?

I've tried using the BeforeInitialBind event to set the controlsource for 
textboxes, using syntax like

txtTwelfthMonth.ControlSource = temp

but I get the 

Internet Explorer Script Error -- Object doesn’t sup****t this property
or 
method: ‘temp.ControlSource’

I'm trying to use this for data access pages based on crosstab queries
where 
the data source is a rolling 12 month, so every month the periods change, 
e.g., 2008-02, 2008-03, etc.
-- 
Christian Bahnsen