"Can I programatically manage Streammanager to start receiving some stream."
Yes you can, using the Wowza IDE.
However, I suggest simply altering your VLC command. You can specify the port to publish to when using RTP or MPEGTS. Or, with RTSP or RTMP, you can publish directly to a live application by specifying a streamname and bypass the need to worry about ports, and StreamManager altogether. Here is an ffmpeg example:
ffmpeg -re -i sample.mp4 -c:a copy -c:v copy -f rtsp rtsp://127.0.0.1:1935/live/myStream