General plugins

Hello Meir
First I must say that I never have installed or used VB.net as you request, but seems that the "mono proyect" can solve your problem
http://www.mono-project.com/docs/about-mono/languages/visualbasic/
Steps to get code in VB.net runs in VPL
1) Install mono visual basic compiler in your(s) jail server(s)
Command in Ubuntu
sudo apt-get install mono-vbnc
2) Create a VPL activity with your own "vpl_run.sh" to run VB.Net code.Take the default VPL C# script and adapt it to use vbnc
https://github.com/jcrodriguez-dis/moodle-mod_vpl/blob/master/jail/default_scripts/csharp_run.sh

3) Use the previous activity as "based on" (VPL feature) in the other activities that use VB.Net

Best regards

Juan Carlos Rodriguez