4.0/4.1 does not support analogue input. 3.4 did I believe but it was dropped in later releases.
However, you should be able to capture it by using something like ffmpeg or gstreamer to pass it on to tvheadend.
There is some info here https://www.linuxtv.org/wiki/index.php/V4L_capturing
If you do a search online "linux analog capture ffmpeg" (or gstreamer) you should find some info.
You can then use ffmpeg to convert it to mpegts & pipe it into tvheadend using pipe://. See [[Custom_MPEG-TS_Input]] for an idea.