near the start of the installation process, there should be an option to "install now" or select custom/advanced setup. Selecting the latter should allow you to create a partition prior to installing.
I would have thought the install process would be the same from a USB as it is from a CD.
Anyhoo, if the partition manager does not appear during install perhaps you could try clicking the repair link at the bottom left of the windows install menu.
There is a submenu beyond it that has a command prompt. From there you can use diskpart to prepare the drive.
This url might help.