thanks Tim

I tried to put (setq viper-always nil) in my .emacs, and found if putting it
before the vimpulse lines, it disabled vimpulse/viper at all; but putting it
after the vimpulse lines seem to have no effect, the editor remains default in
vimpulse mode.

just thought of toggle-viper-mode function, putting it in the .emacs after the
vimpulse lines, it now works as I hopped.

thanks for help though!

Best, Isaac