vlock from x11?

[sen_ml@eccosys.com]

when i am about to leave my terminal unattended, the procedure i use
currently is:

  -switch to a virtual console using ctrl-alt-fx (for an 'x' which is a
   console -- i.e. not running x)

  -invoke vlock -a

i'd like to be able to set things up so that:

  -i can get the effect of the above but via a single command so i can invoke
   this command directly from x11

  -i can get the effect of the above after a certain period of inactivity

the reason i'm not using x-based screensavers is that i'm unwilling to
disable the ctrl-alt-bs sequence used to stop the x server -- the
sequence is too useful when i'm diagnosing problems.  that leaves me
w/ using things like vlock because the x-based screensavers appear to
be pointless w/ the ctrl-alt-bs sequence enabled (has this changed?
or is my understanding off?).

thanks for any help.

[ this isn't exactly laptop-specific, but i find that i use screensavers the
  most w/ laptops for some reason.  i hope this isn't too far off-topic. ]