This is a question we get asked a lot and the answer is Yes.
PPO allows users to import tasks into PPO using either a native Microsoft Project file(.mpp) or a Microsoft Project XML (.xml) file.
If the alternative scheduling tool allows project plans to be exported in a Microsoft Project format (i.e. an .MPP file) or as an XML file, that is compatible with the Microsoft Project XML file format, you should be fine. Since Microsoft Project is the de facto standard, most tools provide this capability. Bear in mind that you will have to do some experimentation to see whether your particular tool can do this.
PPO also has an Excel template that can be used to export tasks in Microsoft Project compatible XML format. This is perfect for non-MSP users that want to create and import simple project plans. For more information about using the Excel template, access the following FAQ.