It may be possible without additional hardware, depending on the exact nature of the IPTV service provided.
MC supports IPTV channels if the provider provides an m3u file that list all channels and their URLs. Since it is a subscription, they may require user authentication. If so, the authentication need to be in the URLs themselves as we have not implemented any separate authentication methods. The streaming should be in HLS or RTSP.
The alternative method requires a video capture device. The set-top-box provided by your ISP usually has SVideo, Composite, or HDMI outputs. You need to get a video capture card/box that will take the corresponding method for input. Then you can set up the channels as STB (set-top-box) channels. You also need an IR blaster device to emit IR signals to your STB, when you try to change channels in MC.