Simple answer - borrow a cdrom from another machine or buy a cdrom. Install from cd rom.
If your computer does not support bootable cds, use the XP install floppies available from M$.
If those are not options, copy the i386 folder to your hard drive (using FAT32 or FAT)
Obtain a 98 startup disc and place a copy of smartdrv.exe on it
Boot using the floppy, run smartdrv.exe and then run winnt.exe located in the i386 folder
XP install should now initiate