There are two things you need:

A bootable linux LiveCD, preferrably Knoppix, but any other distro with all basic linux tools will do.

Some knowledge on how to use commandline based programs (and perhaps some knowledge with linux in general).

First, make sure to boot with your LiveCD. You won't need to boot entirely into the graphical interface.
For Knoppix, the boot: commandline would be something like:

boot: knoppix 2 lang=your-keyboard-layout vga=normal

You can leave out the vga=normal to use framebuffer instead of plain text mode. Replace your-keyboard-layout (keyboard layout) with your country code: for Belgium (azerty), this would be lang=be; for standard US (qwerty), use lang=  ...