The Adafruit Neopixel library is licensed under GPL v3. You can fork a copy of this library into your own code and modify it to suit your own requirements, but if you distribute your code, your compiled project, or a product containing the library or any portion of it, you must ensure you follow the rules of the license by which the library is governed. Those terms of license may include release of the source code if you use any portion of the licensed library in a product. Opinions differ on the exact meaning of GPL v3 with libraries.
You should be able to copy the library into your own codebase and strip out the color-specific routines, put in your own application-specific data-setting routines, but use the same underlying protocol implementation.