yes, but you should be doing your standard rotation on as many enemies as possible. it helps to have a bard in the party as well because you will run out of mana...probably.

provoke/shield lob any mobs that you lose hate on, riot blade causes trouble with building hate, but it lets you spam flash a little more (i don't recommend using riot unless you know your going to hold hate for the few seconds it takes to do the combo to the next flash).

whether or not you can hold hate on enemies with solely flash depends on party composition, a strategy like this really doesn't work against a trigger-happy df black mage, nor is it going to work against an OCD healer or a AOE spam healer.