The procedure is for the Lenovo Netbook but may also work with other brands in a similar way.
- Insert boot media and start installation
- When prompted, select Custom/advanced setup
- Install on partition where ‘Lenovo’ volume sits
This will add the new OS and keep the older for dual-booting.
partition 1 = general data partition
partition 2 = Lenovo partition
partition 3 = OEM reserved volume