Thanks Rod, I think we should forget about the app, because it generates the printing (simple text) and then sends it to the printer via lpr. So, If I (you in fact) solve the problem:
lpr -Premoteprinter xx.txt
where "remoteprinter" is a printer at my user's place (somewhere in his network), I am done. He is accessing my AIX via internet (web browser), he´s got a VPN.
Regards,
Joaquin