Hi
If I recall the option to change the boot flag is via console during the bootup it pauses an issues a counter for you change the boot options, the recovery procedure is now in the ACNS 5.X documentation
http://www.cisco.com/en/US/partner/products/sw/conntsw/ps491/products_configuration_guide_chapter09186a00801cc620.html#wp1043510
I used it a month or so back when I set the passowrd on Friday night during some testing and the couldn't remember Monday morning!
regards
Mark