• make a new directory in lib folder
• copy there the Makefile from lib/print/ and change the name in it
• add your .c and .h files.

• add to the module's Makefile (replace print with your lib name):

SERLIBPATH=../../lib
# libraries, in the format path/shortname , where shortname is
# what will be used for -l
SER_LIBS=$(SERLIBPATH)/print/print

Compiling the module will re-compile the library automatically if needed (e.g. some change in it).

make install will also re-link the module (needed to change the rpath).