Hi Bernd,
Are you wanting to initiate a drawing tool interactively, or draw a graphic with preset points?
If you already know the points and just want to draw the line, this example here might be helpful:
http://www3.turbocadcommunity.com/tiki-index.php?page=External+Com+VB6+ExampleThere's a lot of extra boilerplate here for absolute beginners, but it may help you out. See the attached ExternalCOMVB6Sample.zip
If you want to interactively collect points from the user, I think things are a bit more complicated (and I'll address that situation as soon as I have a better grasp on it.) However, there is an existing VB6 SDK example that does this with two-point lines: see the attached SDKLineTool project.
Kevan