My break in process is slightly different than most, however I am not a big fan of cake, and usually keep my pipes reamed as close to the briar as possible. This is because I like the sweet taste of the briar when it is heated, and too much cake can have you tasting only the tobacco and cake and none of the briar.
In the past I have experimented with a thin layer of honey, and have also tried wetting my finger with water, and swabbing the inside of the bowl. Using my current process, I find neither of the two necessary.
I simply load my bowl loosely at the bottom, and progressively tighter as I fill the bowl. Then, using my pipe tool or nail, I punch a hole in the center of my tobacco with the nail, which will insure a center burn, keeping the burning tobacco centered, and away from the vulnerable inside walls of the bowl.
Once I have smoked the bowl 2/3rd's to 3/4th's the way down, I will let it go out and completely cool down. Then I will dump any loose ash, reload the pipe, and repeat the process 4 to 5 times. By leaving a small amout of tobacco in the bowl before reloading, I can easily protect the bottom of my bowl from a burnout during the break in process. If I am smoking a Virginia flake blend, I find the center punch technique unnecessary, as most Virginia flakes burn center of the bowl on their own without any special efforts.
My goal here is to simply season my briar, similar the the technique used to season a cast iron skillet. You will find that once your briar has absorbed some of the juices from the tobacco during the combustion process, it will have the ability to withstand the burning process, without the need for excessive cake in order to protect the briar.
Once seasoned, you can keep your cake to a minimum, which will allow you to taste the sweetness of the briar, a characteristic which a meerschaum or cob pipe cannot offer.
If during the break in process the pipe gets a little hot, as kaiser83 suggests, don't hesitate to sit the pipe down and let it cool completely before you relight.