Can I safely use hfsutils to "bless" a folder on an hfs+ partition, using: hattrib -b hfs-path ????

I don't think so. HFS+ and HFS volume headers aren't the same. And if there is a HFS wrapper (which is likely if the partition has been initialised with an Apple tool -- I don't think there is another mean now), this won't be verry useful.

I didn't check recently what's the status of HFSPlusUtils ... http://penguinppc.org/files/users/hasi/ There doesn't seem to be anything like hattrib yet.

And the HFS+ module project, now at http://sourceforge.net/projects/linux-hfsplus/ is not really active either.

Bad news, sorry. Every one thinks one could reuse the HFS/HFS+ code from Darwin, but the one should check the restrictions from the APSL first ...

Hope you'll find a solution, you could maybe use the space in the wrapper as a small HFS partition ?