For that, you need to download and install WinToFlash tool from given link: http://wintoflash.com/home/en/
Once its installed, run the application and create your flash drive as bootable windows XP drive.
Provide the Windows XP file path where Windows Setup files are and choose the USB drive e.g., E:\ as per the screenshot.
This will copy all the windows XP files in the flash drive along with bootable files.
Next, restart your machine and boot your machine using flash drive and proceed with the Windows XP installation.
Please note that this has worked for me. This may or may not work for you.
