Do you think it is to be inserted in VistaPE installation ?
It would appear that you've already answered that question by trying it yourself. The script would obviously require some modification for use with VistaPE. Even apart from that, as the author points out, it's not "portable". It is intended to be pre-configured for use with one particular PPPoE/machine set-up. So, at the very least, you need to know and specify those configuration parameters.
PS : I don't understand how is to be used "internetlauncher.inf "
Like JonF, I find it very difficult to be helpful in the circumstances. For one thing it's hard to know where to begin. Have you configured and examined your own machine's DSL internet set-up under the full Vista operating system? What is your understanding of the two quite dissimilar protocols (Point-to-Point and Ethernet) that are involved? Together, they're a bit like a donkey trying to ride a horse.
Unless and until VistaPE includes something similar to the full Vista OS support for PPPoE, finding an easy solution that requires no expertise whatever to implement seems very unlikely. Fundamentally, it involves creating something like an old-time dial-up point-to-point connection (but without the actual dialing) that operates over ethernet with an IP address.