P.S. I really wish I didn't have to do this.
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Not to clear what "this" is. Thaere are already Windoze compliant tar tools around (GNU). I _think_ the real problem is the Windoze filesystems don't support all the file attributes that a UNIX filesystem does (owner, group, mode, links etc.).

Sounds like you need to
Collect the file attribute information (tar -tvf) into an additional file. Then use GNU tar to untar the arf file. Make your changes, then use GNU tar again to rebuild the arf file.
As the attributes of the files have now been lost you need to recreate them directly.
So you need to write a tool which will parse the info file you built in the first step and directly update the attributes stored in the arf file.
I would suggest skip VB, do it in C. Then you can make use of the GNU source code dirctly. License permitting of course.

Dobbs