Join Date: Jan 2009
Location: Tri-State (IA, WI, IL) area
I'm not so sure about a forelock, but I'll tell you what I did to get Ruby's tail to grow out - keep it braided, don't brush it, wash it maybe once a month ('course unless her forelock is getting really dirty for some reason, probably wouldn't even have to bother with washing it much.), and use MTG.
In the meantime? You could always make a little forelock extension for her... just clip some hairs from the underside of her tail, gather them together over her current forelock so that the clipped ends are about where the headband of her bridle/halter would be and ley it out however you like, then run it through a sewing machine a few time so it'll stay together. Then you can just bobby pin it over her forelock, and sort of hide the bobby pins/sewing with her halter or bridle. Trim as necessary.
As long as she doesn't get to wild about tossing her head or someone doesn't come along and pick at her forelock, it should stay in pretty well. I knew a girl who had one of these made of for her horse, and she even ran barrels with it on.