As with FCS3, best recommendation is to use a dual partition scenario.
As FCS2 was built to be optimized for OS X 10.5.5, you may be able to get reasonable performance on newer Mac OS X versions, but I would stick to installing, at most, OS X 10.7.x (Same for FCS3) After that, there will be some glitches in some of the apps (Motion comes to mind).
Even with the first versions of FCP X (OS X 10.6.8 minimum), having each Final Cut version on discrete partitions was the most recommended procedure.
That being said, once FCP2 is installed on the second partition, boot back into OS X 10.11 and try launching the apps on the second partition. Motion will be completely dead, DVD Studio Pro will be flaky, and the other apps will have limited functionality, if you can even launch them.
Even in OS X 10.10, FCS3 was hit and (mostly) miss.... FCP is the most stable, but I still have some problems. If I need to edit older projects, then I boot into Lion. With my iMac 27" Late 2009, the FCS3 apps scream!!
Good Luck