Yes you can but it's not a straightforward process. I did it for my chromebox which follows the same procedure as doing it for a chromebook. Basically you have to open the machine and remove a screw to enable write access to the bios. After that you have to replace the coreboot bios that came with the computer with a newer coreboot version and install SeaBios (old bios emulation on top of coreboot) as a payload. You could also have a linux kernel as a payload but this was more complex and I didn't need faster boot times.

Once all this is done, the laptop behaves much like any other laptop except you have an open source bios. You can then install linux on it from a USB key like you would on any other device. I imagine the quality of the drivers depends on which chromebook you use. I hear the chromebook pixel has excellent support and that's no surprise as that's what Linus uses (or used to, I'm not sure if he changed).