pgtcl way of specifying a user

I have cron and init scripts that call my PostgreSQL db for their data.
This worked fine until I moved the sql server off the system.  Then I had to
specify the actual host and user in the case of pg_dumpall called from a tcl
script.  Cron wasn't grabbing the proper variables of PGHOST PGUSER I guess.
No problem, just added them to the command of pg_dumpall and the script
works fine

I have another script that uses libpgtcl and this script runs as part of
init level 3 or level 5.  It also don't connect to the database by utilizing
any variables in a .bash_profile config file.  I can not figure out how to
make the connection.  I used:

  pg_connect $PGDBName -host $PGHostName

and this works, but I don't know what user it will use as part of init and I
can not figure out how to define a user.  Can anyone shad some light on my
problems.  IWAI