If you have a DragonFly 3.2 system and you want to try the 3.4 release candidate, you can delete your local source, edit the Makefile to pull down 3.4 instead of 3.2, and run it.
rm -rf src
(in vi) :%s/DragonFly_RELEASE_3_2/DragonFly_RELEASE_3_4/g
(save, quit vi)
… then proceed to make buildworld and so on, as normal.
The caveats: I haven’t tested this yet, and this assumes you don’t have any local changes in /usr/src that you want to save. The usual warnings about lighting your computer on fire, etc., apply.