1) Enter BIOS and set SATA Controller Mode to "AHCI".
2) Reboot and use F12 to select your external CD/DVD drive as the boot device.
3) When it says "Press any key to boot from CD/DVD..." DO NOT PRESS ANY KEY - WAIT.
4) It will then either boot straight from the DVD or it will once again say "Press any key to boot from CD/DVD...", but in a slightly different font. This is when you need to press a key.
5) Click through the Windows 7 install process until you get to the point of selecting the drive you want to install onto.
6) Delete all of the partitions listed there until it says just "Unpartitioned Space".
7) Click on New, and then OK on the prompt. Setup should create TWO partitions now - one that is 100MB and one that is the rest of the capacity of the drive. If it creates 3 partitions then you have done something wrong, as it is installing using UEFI BIOS not Legacy BIOS.
8) Once Windows has installed, install the WLAN Driver and then Lenovo Energy Management (although the default Windows drivers worked straight away for me).