Yes, it is possible. Although, with some caveats. Firstly, I have no idea
how to go about making a bootable USB flash drive. Only if you can still
get to Windows XP, even in safe mode, should you be able to do this without
the need to. First copy the entire XP CD (using someone else's machine, of
course) onto the flash drive then take it back to your computer and run the
x:\i386\winnt.exe file. It will behave exactly as it does on the CD. If
you need to do a "clean install" from scratch you will also need a set of XP
Boot floppy start-up disks. You can download these for your version of
WinXP (Home, Pro) from:
http://support.microsoft.com/kb/310994
Then go down to the middle of the page and select either Windows XP original
release, Windows XP Service Pack 1 (SP1) or Windows XP Service Pack 2 (SP2)
and, of those, either Home Edition or Professional.
After your computer has booted from these disks, type in the location of the
i386 directory on the USB flash drive when prompted