On a unix system, there's databases of terminal descriptions mapping
such functions to the byte sequences to be sent to the terminal:
termcap (older) or terminfo (newer).  The terminal used is indicated
by the TERM environment variable.  So you could get the content of
this variables, and read the termcap or terminfo files to collect the
byte sequences to send to move the cursor at a given position.

Or, you could use the curses (or ncurses) unix library which does that
for you.  There's the cl-curses Common Lisp package that implement the
FFI to the curses unix library.

If you use clisp, you can also use the clisp specific SCREEN package:
http://clisp.cons.org/impnotes/screen.html

(screen:with-window
  (loop for x from 0 below 3
        do (screen:set-window-cursor-position screen:*window* 4 10)
           (format screen:*window* "~4D" x)
           (sleep 1)))

Now, if you just want a quick-and-dirty solution, you can use the
Carriage Return ASCII code, in most terminal it will move the cursor
at the beginning of the line without advancing to the next line:

(loop for x from 0 below 3
      do (format t "~C~4D" (code-char 13) x)
         (sleep 1))

(it even does the right thing in emacs inferior-lisp buffers, which is
not the case of screen and other curses libraries).

Or you could use directly the byte sequences understood by your terminal.
For example, if you know your terminal understands ECMA-048 (ie. ISO6429),
then you could use:

http://darcs.informatimago.com/local/darcs/public/lisp/common-lisp/ec...

(asdf:oos 'asdf:load-op :com.informatimago.common-lisp)
(shadow '(ed))
(use-package  :com.informatimago.common-lisp.ecma048)
(generate-all-functions :compile t :verbose t :export t
                        :8-bit nil :print t :result-type 'string)
(loop for x from 0 below 3
      initially (ed 2)
      do (cup 4 10)
         (sgr (+ x 31))
         (format t "~4D" x)
         (sleep 1)
      finally (cup 22 0))

--
__Pascal Bourguignon__                     http://www.informatimago.com/