Configuring AT scheduler w login script

I’m trying to add entries to the Task Scheduler of NT 4.0 clients via login scripts w/ AT command. Problem: when the user logs in, the script fails due to insufficient user access. How do I over come this? I could configure this to do be done in the context of the local system account? I’ve tried the RunOnce parameter. I should change the acct the Task Scheduler uses? Thx.