samba - Nov 2003 - allow writing, but no overwriting or deleting

Hi,

I've got a directory on a fat32 partition for which I want to grant
write access so that people can store files in that directory, but I
don't want people do be able to delete or overwrite existing files or
subdirectories in that directory. Any ideas how to get samba (version
2.2.8-SuSE) work this way?

Thanks in advance!

Michael.