Unusual setup

[zwolin]

I would like to input 3 video sources from webcams (3x 1080px x 720px resolution) with a small overlap into one big 1080p video, then encode it and stream it to livestream.

I tried to use wirecast, vidblaster, xsplit, vlc and many less popular pieces of software and I failed. None of these programs would let me rotate webcam video 90 degrees.

Do you know any live streaming software that would let me combine a few video cameras into one live stream? Maybe something that would let me stream in a custom resolution and stitch webcam streams together?

If you had an assignment like that - how would you tackle the problem? (the bottom line is - obtain a live stream from multiple webcams combined into one common viewport. The result should be higher than wide - I will build a custom flash player).