Never heard of anyone using Vaseline or any other kind of viscous lube for bearing edges. Honestly, it doesn't seem like it would work all that well. What doesn't get wicked into the fabric will just get "squeegeed" out as the head moves across the bearing edge.
Like the other guys have already mentioned, paraffin wax is a commonly used bearing edge lubricant. Just rub the stuff on like a crayon. It'll stay put, won't wick or displace under tension, and won't melt or run.
I have heard of people using Vaseline to lubricate tension rods, but lithium grease does a much better job. Unlike Vaseline, lithium grease doesn't thin out and run when exposed to summertime heat.