- Create Loki Live-USB
- Boot Elementary from that USB.
- Open "Application" and run Gparted (There you can change your partitions)
- Then click "Install Elementary"
- Click on "Something Else" and click "Next".
The next screen may look rather intimidating but it is just showing your current disk layout.
Look at the image above. You will see all partitions on your disk (you can change disks in "Device for boot loader..."
Choose free disk space there you want to install OS.
You need two partitions.
When you have found the partition with free space, click on it and press the plus symbol (+) under the disk layout. If you want to delete partition, click minus symbol.
First, swap partition. Choose disk space you want to use and create logical partition:
It's recommended to create swap around 1GB or the size of your RAM in case you want to be able to hibernate your system (not possible on some machines).
Then create / partition. Choose your free space, set size you want, when create primary partition with mount point "/" (it's means root) as Ext4 file system.
Press "OK" and then "Install now" to continue.