First of all, you did not develop the CEPC BSP so you should not change any code in place. First clone the CEPC BSP (using the Clone BSP command from the Platform Builder menu), then copy INTR to \PLATFORM\YourBSP\SRC\... and modify dirs to build your INTR version. Whatever folder you like. Just make sure it gets build before any library that uses the lib INTR makes (see SYNCHRONIZE_DRAIN and SYNCHRONIZE_BLOCK).
RE: Thanks for your answer
First of all, you did not develop the CEPC BSP so you should not change any code in place. First clone the CEPC BSP (using the Clone BSP command from the Platform Builder menu), then copy INTR to \PLATFORM\YourBSP\SRC\... and modify dirs to build your INTR version. Whatever folder you like. Just make sure it gets build before any library that uses the lib INTR makes (see SYNCHRONIZE_DRAIN and SYNCHRONIZE_BLOCK).
To answer no 2: Yes.