You can't. Given that most, if not all, IPTV providers are merely pirates they've pretty much been banned from the Roku platform. If you come across a site that tells you how to sideload it, don't. You'll just have it automatically removed and the ability to sideload will be forever blocked.
Roku Community Streaming Expert
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Great! But how did you get it to work? I got it to load, but when I plug in the username, password, and url, it gives me an error. I know the information I am providing is correct, because it works on every other device. Is there some trick I am missing?