You're typically free to use whatever you like in your own plugins. As of Liferay's core: It's fully tested with the version that it comes with. Exchanging it will mean that nobody but you has ever used it in this combination.
Is there a way? Yes, sure - drop in the new library, remove the old, check if it still compiles and make changes as necessary. Test *everything* and don't complain to anybody if you missed something. Do this again when the next security patch or GA version comes out. Always remember: You're the only one who's running this combination.
If you want to lobby for this to be done in the next version (e.g. current master), you should lobby for this on the
Ideation pages and get support for a feature request.
In addition and somewhat related: If you actually wish to upgrade (and if you're on 6.1 CE), I'd suggest upgrading to Liferay 6.2, as you can get security fixes and updates for this version (until 7.0 is out). 6.1 CE didn't receive any attention in a long time now and you should rather invest in the future than the past.
