I did exactly that last week. Fully pasted a board, starting installing all the main component, moved to the caps and resistor to realized I was missing a bunch !!!
I made these for the exact reason Steve is pointing : I got a TT .. without PSU .. this was the easy way to get it powered.
Now I'm glad it can help other people in similar situation.
Rodolphe
I use Eagle 7.7 (on Mac ) and PCBWay for all my PCB. They check the file you send before letting you pay, work with you on fixing issue and shipping is fast.
on command help, the bracket are here to show you the parameter is optional, they are not part of the command options, so [user] mean that you should replace [user] by the username .
If you don't specify it at all , it'll ask for it.