Use WMI to manage bios update through vbscript

I am attempting to create a vbscript to update Dell bios's.

Is there a way to use wmi to disable the system password before updating a bios? or is there a way to update a bios with the system password enabled?

I am using psexec to connect to a remote computer and issuing the following command

xxxbiosxxx.exe /s /r /bls /p=password /l=c:\windows\temp\dellbiosupdate.log

This works from the psexec session if executed from the command line but does not work if executed inside vbs.

Is there a way using vbscript or powershell to obfuscate the system password.