remote dumping of databases

hi,
got a question, i tried to find my answer in the documentation and mailing
list archives, till now with no luck.
I've got multiple virtuale webservers with customers using a remote pgsql
server where they don't have access to.
All access is done with clients and scripting languages from the
webserver.
Now I want them to be able to dump their own database. And when I use the
command without piping the result to a file everything works.
(pg_dump -h <remote pgsqlserver) -u <dbname>.
You get the user prompt and password prompt..How ever..how do you get the
content of the dump to a file??? Every pipe action will result in endless
waiting, pg_dumps waits for the username/password.......

Is there an solution of do I overlook something here???

bye

Frank