http://support.lenovo.com/en_US/research/hints-or-tips/detail.page?&DocID=HT073837

Get the latest ISO file from http://support.lenovo.com/en_US/downloads/detail.page?&DocID=DS029170

• Currently it's http://download.lenovo.com/ibmdl/pub/pc/pccbbs/mobiles/g5uj21us.iso (version 2.58)
• Get http://userpages.uni-koblenz.de/~krienke/ftp/noarch/geteltorito/geteltorito.pl or http://colimit.googlepages.com/isobar.c to extract the boot image from the ISO file

perl ./geteltorito.pl g5uj21us.iso > boot.img

or

gcc -o isobar isobar.c &&
./isobar g5uj21us.iso -o boot.img

• Copy the boot.img to a USB device ( make sure to use the correct device, otherwise you might delete your data)

dd if=boot.img of=/dev/sdb bs=512K

• While booting press “F12” to enter the boot menu and select the prepared USB drive to boot from