Is there away where I can get Tk to represent this data in a directory like hierarchy structure, similar to Tk::DirTree. So I can have a display of folders representing the Business Units, then inside those folders another folders for Groups and then for functions?

Yes, just do what Tk::DirTree does (Tk::DirTree is pure perl, so Use The Source Luke).

Also, if I read the above data into a hash then can I use TList to do the job?

Sure, why not.