To actually alter the visible command line, you can assign to the vari-
able $0 as documented in perlvar.  This won't work on all operating
systems, though.

##</code><code>##

$ perl -e '$0="foo"; 1 while 1' &
[1] 19748
$ ps U blazar
  PID TTY      STAT   TIME COMMAND
19585 ?        S      0:00 sshd: blazar@pts/0
19592 pts/0    Ss     0:00 -bash
19748 pts/0    R      0:06 foo
19758 pts/0    R+     0:00 ps U blazar