I personally have suffered two front-wheel slide-outs, one on the road and one on a dry singletrack.
Here's the road one:
Having more weight on your front wheel will temporarily increase the size of the contact patch. If your bike+rider is 200 pounds, and your tyre/tire pressure is 100 PSI, then each tyre is supporting 100 pounds, and will have a contact patch area of 1 square inch (imperial measurements work quite nicely here, sorry)
So if you load the front wheel with another 5 pounds, the contact patch area will increase by 5%.
Downside, if you're going to slide out anyway, adding weight to the front at the wrong moment will make you go down harder.
Also, weight on the front is weight that has come off the rear. A rear wheel step-out is more controllable, but still not a pleasant experience.
The best answer is to hit the corner at a speed you can manage, not too fast, but fast enough to carry momentum through the turn.
Notes: the above video is from the handlebars. Its a steep lefthand bend, renowned for the "kick" on the leftmost side. Exacerbated by the white painted line and that I was braking into the corner. I managed to recover the front wheel slip, but by that time I was going across the road. Another metre of road and I would have regained control.