I use this foam roller
DON'T ROLL THE PART BY YOUR KNEE--stop before your knee. you're stretching out the band from the hip down, but not where it connects at the knee--you'll screw it up worse.
And I wear these straps
(they def help--forgot them on my last 10K and could tell the difference, especially afterward)
There are two stretches that help: one you can do easily on the fly--just stand up, cross your legs with feet together and push out the hip of the leg that's behind the other.
the other is the sort-of Indian style thing but switch your legs--if it isn't super tight at your hip, then you're doing wrong.
Stretching your legs in general helps take pressure off ITs.
Also, increase lateral leg strength with machines, wall sits, lunges, etc.
Avoid treadmills and do old-school stairmaster if you must train indoors. The repetitive motion of running in a perfectly straight line strains the ITs. At least change the elevation of the treadmill and limit to a couple miles if you must use one.
Finally, get fitted properly for shoes if you haven't, and consider custom or semi-custom orthotics.
When i was a teen and in great shape, i couldn't make it through a soccer game or 5K without serious pain. 25 years later, i can do 10 miles with little pain. I don't like to push beyond that and get bored with running anyway.
For some reason biking is probably harder on my ITs than running. Skiing is my favorite exercise, and it does nothing to them. Of course, swimming is great no-impact training too.