Actual language independance couldn't probably happen because languages have so many differences between them. Seems simple enough if you have a parser instead of translating to bytecode, assembly (or whatever lower level logic representation) you have it translate to another language. This would only work if different languages both had completely equal sets of possible operations. Basically if C# does something that C++ can't do, you have to rewrite the C# code to be compatible. If I write a Java program and relax your inheritence relationships somehow to work with C++, I just stopped using Java's advantages. However if you are just talking about simple operations and have just syntactical differences then you can translate.

for example
dim varA
is compatible with my $varA
but dim varA in C++ would be a WTF. it doesn't know if it's an integer,character, or whatever.

I'm tired and rambling, I hope you understand that.
Check this out.

http://seclab.cs.ucdavis.edu/~devanbu/dp.tex.pdf" rel="nofollow">http://seclab.cs.ucdavis.edu/~devanbu/dp.tex.pdf">http://seclab.cs.ucdavis.edu/~devanbu/dp.tex.pdf" rel="nofollow">http://seclab.cs.ucdavis.edu/~devanbu/dp.tex.pdf

-K