How do I install a boot manager that works with Ubuntu and Windows 8? (Legacy)

How do I install a boot manager that works with Ubuntu and Windows 8?
(Legacy)

I'm in an interesting place. I have both Windows 8 and Ubuntu 13.04
installed on different partitions, both accessed through legacy boot. This
machine came with UEFI by default. Anyway, the only way I can switch
between the tow OSes is by changing which one has the "boot" flag from a
Ubuntu live USB.
How can I install a boot manager after having the OSes already installed,
where I can select which one I want to use when I turn my computer on?