get a full taxonomy path from Bio::Taxon

In 2003, there's an old post asking about a way to get a full taxonomy.

http://osdir.com/ml/lang.perl.bio.general/2003-08/msg00206.html

Then Bio::Taxonomy is deprecated and now combination with Bio::Tree has to
use in order to work out the story. 

In 

http://search.cpan.org/dist/bioperl/Bio/Taxon.pm

it also gives an example by explicitly stating what to retrieve. However,
what I need is to just provide a GI or accession number and to get a full
taxonomy and I find there is no simple way (at least I don't know .) to do
so. Would anybody advise?

Thanks a lot,

Ross