I've never used VXML myself but since it just yet another XML application I guess it should not be hard to do it in Perl which has many modules for XML support.

Anyway quick search on google revealed following article: Creating VoiceXML Applications With Perl.

--
Ilya Martynov, ilya@iponweb.net
CTO IPonWEB (UK) Ltd
Quality Perl Programming and Unix Support UK managed @ offshore prices - http://www.iponweb.net
Personal website - http://martynov.org