The work was done in MDL-19125.
http://docs.moodle.org/23/en/Administration_FAQ#How_can_I_fix_just_one_bug.2C_without_upgrading_my_whole_site.3F may offer some advice.
You probalby only need to back-port the core changes, and add the requireed capability to the certificate module. (Acutally I think the certificate module maintainers have already done that.) You don't need to add all the new capabilities to all the core modules. You can wait until the whole site is upgraded to 2.3 to get those.