How to travel into the future?

[Marcin Borkowski]

Hi list,

I'd like to use in my code the M-n facility in history to enable the
user to have access to a reasonable default value, as described in
  (info "(emacs) Minibuffer History").
How should I do it?  Should I use read-string?  If so, do I have to put
the default into the history variable and use the (HISTVAR . POSITION)
argument to read-string?  If so, should I then manually delete the
default (which might have been used or not by the user) from the history
variable afterwards?

Any pointers?

TIA,

--
Marcin Borkowski