I have the bootloader/fastboot drivers installed. When I type in "fastboot devices", it shows up in the list. The only place I can't get ADB to see it is in recovery itself. In device manager, during recovery, it shows up in "Other Devices" as Nexus 10 with an ! symbol, but uninstalling and reinstalling the drivers does nothing. I just get the ! symbol again.
EDIT: I uninstalled the "Nexus 10" drivers and installed the generic "Android ADB interface" drivers and it recognizes it now, but the "sideload" command doesn't work. I get *cannot read 'sideload' *.