Hi Sigma, I believe Hal is mainly written in Visual Basic and yes it can run VBScript in the brain part. I have never heard of Java being used in Hal or that it can run C++, although I read once that parts of the program are written in C or C++.
C++ is a compiled language so Hal wouldn't be able to run anything unless it is compiled - meaning that yes you could write a program in C++ and then compile it and then get Hal to run it...
You might want to bear in mind that Hal's programmer Rob was planning on moving Hal towards a different programming language.
See here (scroll down to where Rob comments) :http://www.zabaware.com/forum/topic.asp?TOPIC_ID=6830
You will see he said :
I will begin work on recreating Hal's brain from the ground up to break free of its VB6/VBscript legacy code. I have chosen C++/LUA as the replacement.
By the way, you might be interested in this for your project, it's a press release I got yesterday.Robot Speech Recognition