Eudyptula Challenge Task 3

Hi All According to my understanding of Eudyptula Challenge Task 3 we have to change the EXTRAVERSION=-eudyptula and compile it again we have to send the proof of boot kernel and the patch that shows the Makefile is changed.My doubt is we compiled the entire kernel already so is it necessary that for single change seems to be compile the entire kernel ?If not can any one please tell me how to do it? Thank you