From Codtech

This is perhaps the easiest way to change an image parameters in a CULT classic custom or PXES Universal Linux Thin Client CDROM.

In network boot, for example, you can just edit the Boot loader configuration file to add, modify or remove options.

Using GRUB edit

• highlight the desired menu entry to edit
• press  e  to edit (be careful because if you don't read the bottom message and you press  e  to edit when the file is password protected, edit seems to do nothing, see next step)
• if the configuration files is password protected you need to press  p  for password and then type in the correct password and the extra features, like edit, will be enabled
• highlight the kernel line if it's not already highlighted and press  e  again to edit
• add or change the desired parameter or value
• press  Enter 
• press  b  to boot
• or press  ESC  to undo the changes