doing an upgrade from a flash drive

[Steven Bellovin <smb%cs.columbia.edu@localhost>]

I'm currently building a 5.x .iso, via the usual mechanisms.  Is there any easy 
way to copy everything to a USB flash disk, make that bootable, and do the 
upgrade from it instead of from a CD I can burn?

                --Steve Bellovin, https://www.cs.columbia.edu/~smb