You can use a built in method to get the equivalent color value to use in your application:
Dim myColor As Color = Color.Red
' Translate myColor to an OLE color.
Dim winColor As Integer = ColorTranslator.ToWin32(myColor)
The result is an Int32
which is a Long
in VB6
So...
In your VB6 control you can expose a Color property like this:
Public Property Get ColorValue as Long
ColorValue = lblColor.BackColor
End Property
Public Property Let ColorValue(value as Long)
lblColor.BackColor = value
End Property
Then in you VB.NET application you can set it like this:
MyControl.ColorValue = ColorTranslator.ToWin32(Color.Red)