Is it possible to run fastboot in a recovery mode shell (without connecting to PC)?
Fastboot commands are for the bootloader, not recovery, so even if you send the commands from recovery, it would do no good since you would be in recovery, not the bootloader. 

According to all the information I could find about this "tablet," including information from HP, indicates that there is no way to access fastboot since there is no USB port and HP doesn't make a dock-port to USB cable for the tablet. Edit: apparently HP does have a cable for it, but it may be difficult to find and isn't cheap.