A few things of possible interest poking around the vxworks console
set deploy Set or display the system debug flag.
..
[vxWorks]# set deploy
The system policy mode is set to 'field' (deployed mode is on).
[vxWorks]#
Is there an interesting debug mode?
set bootline Change the boot line
show bootline Display the boot line
show bootline
boot device : tffs;usb
Maybe possible to change boot order?
The boot order can be changed using (cmd)#set bootline , just as you suspect. It doesn't seem to make much difference, as you can force the USB boot using the power cycle trick.
I am not certain about the deploy flag, but the VxWorks shell has some pretty potent debug capabilities, including searching the symbol table, stopping and restarting running processes, setting breakpoints, executing loaded functions directly from the command line with parameter passing, examining and modifying memory, disassembling functions that are loaded in RAM, and more.
By the way, for moving small files, you can log in via ftp and telnet; you can ftp small files to/from /ram0, and then within the shell move files between the /ram0 and the "bin" directory or elsewhere. For larger files, such as a .bin file, a small usb stick works the same.