I can't find the thread, but there is also a lot you can do with your gait and footstrike. (Someone had posted a question about a year ago on rolling ankles when wearing crampons, and I posted a detailed response, but the thread seems to have disappeared; maybe it was another forum?)
In any event, yes to poles, they help a lot. An emphatic "No" to big heavy boots. I agree with jniehof, the heavy boot makes it worse. I've been in trail runners exclusively for about 8 years now, and I roll my ankle much less often than I did in boots, even though I am a lot older. The boot puts a big unnatural platform under your foot, that acts as a lever to roll your foot over. The only boot that will really prevent ankle roll is a well fitted and fully laced plastic boot, which is basically a cast. You don't want to hike in those in the summer!
Regarding what you can do to minimize these events while actually on the trail: Watch where you step. It sounds obvious, but it takes a lot of concentration, especially if you are moving fast. Keep your feet somewhat everted (splayed, the opposite of pigeon toed). An everted foot is much harder to roll. And make your footstrike with your foot somewhat dorsiflexed (toe up). This requires a little shorter stride, as you will be more "over" your foot on the footstrike. The dorsiflexed foot is much harder to roll.
Good luck.
TCD