Screenshot below should make it clear that it's possible to add an embedded IronPython commandline into Visio 2007.

 

image

The script in the window is here:

c = Isotope.Color.RGBColor( 1, 0.7, 0.3 )
print c.ToSystemDrawingColor()
shape = visio.ActivePage.DrawRectangle( 0,0, 2, 2)
AutoVisio.VisioLib.SetFillColor( shape, c.ToSystemDrawingColor() )

The output is the orange square.

This is stage 1 in my side project of providing a NodeBox-like experience to Visio.

I'll post the source once the overall user experience is better. (It turns out a multi-line TextBox is not he best IDE experience.)