I know how to set the shape forecolor if I'm programmatically creating them.

Code:

MapPoint.Shape blah = axMappointControl.ActiveMap.Add[Shape]([Parameters]);
blah.Line.ForeColor = 0xFF00FF;

I also know how to set the shape forecolor after the user draws the new shape.

Code:

private void axMappointControl_SelectionChange(___)
{
   MapPoint.Shape shape = axMappointControl.ActiveMap.Selection;
   if (shape != null)
   {
      shape.Line.ForeColor = 0xFF00FF;
   }
}

But I was wondering if there was a way to (programmatically) set the forecolor. So while the user draws new shapes, the forecolor is the appropriate color.

You could check the ActiveMap.Selection property in the AfterRedraw() event. If it is a shape, then set the forecolor property.