Just cut straight down through the flat, and cut off however big a chunk of the point that you need to remove to make it fit on the grate, and lay that chunk on the grate next to the rest of the brisket. I look forward to that chunk now - burnt ends for breakfast! Yum...
When you trim fat off, save those big hunks of fat and lay them under the ends of the brisket so that the fat hunks, which would have been waste anyway, catch the brunt of the heat coming around the edges of the waterpan. Works great for me.
I used to wrap the end of the flat in foil, but I find I like the protection of the fat chunks better, actually. I've also done as Jim mentions above many times, separating the point and flat and sliding back on top of each other, as I have a bad habit of buying BIG briskets on a pretty regular basis.
Keri C, still smokin' on Tulsa Time