AutoHotKey can help you. It's free and opensource application, which can be used for keyboard remappings. With this program you can do some remappings. For example, you should be able to remap "RightAlt+i", ..., "RightAlt+;" to the number pad keys. You can see an example here. You can download it from the official website.
You can follow the instruction in the "Special keys" subsection of the official documentation to determine, if it's relatively easy to remap Fn key in the case of your laptop. If Fn key is observed by the "Key History" page, then the "Special keys" page explains, how to remap it. Otherwise it may be hard to remap it (here is my question about it).
Edit: You may also like to see a very detailed guide "The Mystery of the FN Key", written in the comment below by Synetech.
Fnkey is special and almost always handled by the keyboard controller and never visible to software, so you can rarely, if ever actually remap it. – Synetech Sep 05 '12 at 18:48FNKey gives an in-depth way to remap it in OSX on certain Apple systems and when using a specific Apple keyboard with Windows. If you’re lucky, you can do it, otherwise there’s really nothing that can be done short of replacing the keyboard controller. – Synetech Sep 06 '12 at 01:33