use strict; 	# always do this

  my $line;  	# this will contain the current line read
		# from stdin. We could also have used $_,
		# but using $line is less cryptic
  my $counter = 1;
		# This is the counter of the urlXX= string

  while (<>) {	# while we get input, we read it
    $line = $_;

    # Munge the current line into what we want
    $line =~ s!^http://!url$counter=http://!i;

    # BastardOperator made a post below that got me thinking.
    # Maybe you want it this way :
    $line =~ s!&!item=!g;

    # but maybe you want item1=bla item2=ble etc.
    # This line will do the second :
    my $itemcount = 1;
    while ($line =~ s/&/$itemcount++/e) {
      # the action is in the while statement
    }

    # and print it
    print $line;

    # and increment our counter
    $counter++;
  };