I've heard that on the new ones they've illegally made it not possible anymore, but haven't experienced direct evidence of that yet. For mine I had to remove a screw from the motherboard but it wasn't that difficult. Not much worse than jumper for boot order in ye olde days
The new procedure is boot without the battery connected to enable writing to flash.
My suggestion? If you want a Chromebook to run Linux, look for surplus school laptops instead. My throwaround workshop laptop is an Asus that to me looks like it was clearly sold in an educational Chromebook format as well--partially ruggedized, partially waterproof, 12", N100, plastic blank where the camera should be, still only $120
Basically, if you're lucky, you can find Chromebook-class PCs with less restrictions. Admittedly I'm in a lucky locale for such things, but the one in question i bought from a normal retailer