Batch script help

[Wurlit]

Hello, i'm trying to batch convert a few hundred .avi to .mkv files through scripting. Looking at the wiki, it seems that a few audio commands needed for the conversion are missing, or i just can't find them. I'm new to scripting and every guidance would be helpful. Specifically, the .avi files have two AC3 audio streams, first is stereo and second is 6-channel. I want to copy the video stream but remove the first audio track (2-ch) and keep the second, english (6-ch) track. Then i remix this to 192kbps stereo AC3 (lav) and save it in .mkv container. I also attach two pictures from the program, one showing the settings when i import the file and another with the above settings that i want to set. Thanks for any reply.