Hi. Thanks for the questions... When Interactive User Import was initially designed/released the module was setup to use the scheduler for several reasons but specifically performance and timeout issues with large implementations... Since the initial release though we have had many customers request additional features so we are on the process of reviewing and adding these. The biggest request is the ability to use a static file and make the imports recurring. We currently have a client that is paying for these enhancements to be added before the next release so this is speeding up the development process. Within the next release (should be 2-3 weeks out) you will be able to specify a static file, make the import recurring, and also implement other feature such as importing only a specific number of users per import run, setting up a global filter which must match before the record is imported, and other logging enhancements within the scheduler. If you currently own IUI and want to receive the beta for this next release please open a support ticket on Snowcovered and we can provide this.
Here is a screenshot of these upcoming features...
Also... regarding your enhancement requests, we will review this for future updates. Its possible you could use another module (such as our Dynamic Forms) that would then allow the user to upload a file and with some behind the scenes to accomplish your needs.
-Chad