I am using Xquery as a means to connect to an Oracle 10.2g database. My apologies if I did not make myself clear about that in the original post.
But from your answers, it appears that there is not currently a way to do this in Perl, and nobody has written a module to directly support it. I incorrectly assumed that, since Oracle treats xquery as a subset of SQL, the DBI module would allow it. I guess I will have to go under the covers and find out how/if the xquery translates to SQL and write it all out, or use the Java Saxon libraries instead.