Avoid recompile when add ThreadX Source

I need to change some features of ThreadX in my project, so i added ThreadX as source. Because of that i need to recompile ThreadX each time i run clean, and this causes long compile time. After first build i do not change any configurations of the ThreadX, so there is no need for building ThreadX source each time i run clean. How can i add modified ThreadX build to project in Eclipse?