Yes, Google used to do that in its Google Toolbar plugin (overriding the user's new tab page preference), and Microsoft asked Google to stop.
You can design your own new tab page, and ask the user to set it as the new tab page. It is like the homepage, replacing it without asking the user is annoying.
The following is signature, not part of post
Please mark the post answered your question as the answer, and mark other helpful posts as helpful, so they will appear differently to other users who are visiting your thread for the same problem.
Visual C++ MVP