relocate office for mac outlook data file

Does anyone know how to relocate the Outlook storage files? I would like outlook to store the data files in an external hard drive, so that I can point my iMac at it, and then when I take my macbook and external hard drive on the road, I can simply point my macbook at the same location.

On windows it was simple, as you simply cut and paste the .pst file, and then redirected outlook to the new location

any thoughts?

Thanks