VESA BIOS Extensions: How to Change Resolution?

I just finished writing a small boot loader and kernel that switches into protected mode and sets up a basic physical and virtual memory m开发者_开发技巧anager:

Currently, I'm displaying text onto the screen by writing to the video address 0xB8000 in memory. However, I would like to increase the TTY resolution, the way GRUB does (through, I think, the GRUB_GFXMODE flag).

How do I increase the screen resolution in protected mode?

I've tried looking into the GRUB source code (regarding the parts that concern VBE and vbeinfo); however, I don't understand how it's actually working. Is there any guide online for how to do this? (My search on OSDev.org didn't yield much, but it's possible I missed it.)