Setting up SAML for Box is straightforward. First contact your Box account manager and ask to have SAML enabled for your account. You will then be asked to provide a SAML metadata file, which they will need in order to validate SAML responses coming from OneLogin. The metadata file can be downloaded from OneLogin in the sidebar on the page where you edit the Box.net app.

Also let your Box account manager know whether you wish to disable password-based login and thereby force users to only access via OneLogin.