I seem to have figured it out, but it was more complicated for me than I've read so far in this thread. I got to the point if pushing files onto my N10 during recovery, but--and I don't have good information here or knowledge to speak about it--there seemed to be some issues surrounding /data being mounted or not during the push, needing to be unmounted or otherwise when trying to then flash in recovery, and many times I found that the files I had pushed were no longer there if I rebooted recovery. Also, correct me if I've misunderstood, but because the N10 doesn't have any physical external storage, the filesystem with most ROMs, especially the stock ROM, creates symbolic links of /sdcard and maybe others.
All told, I ended up using the Google stock images, which completely wipe the device and recovery partitions, downloaded the ROM files I wanted, flashed a recovery, booted into recovery before the Google stock image could overwrite my recovery, and luckily found the custom ROM files I had downloaded. I wonder if my file system is a hack though because of that?
Also, it seems like the optimal way to go is through adb sideload (I don't have any external flash drives) but I thought that was reserved for apps and not complete roms.
Nexus 10 (16gb Wi-Fi)
CM10.1 20130313 Nightly
Stock Kernel (interactive/noop)