First off, the code I am attaching is not pretty, and there may well be a LOT better way of doing this, but I hope I am at least on the right track.

Also, I noticed in your code, you referenced tel_no, but the XML file has tel_num... I will assume tel_num is correct. I also noticed the following was probably a typo:

$parm_str = "\$" . "config->{jane}->{tel_no}, "\n";

$parm_str = '$config->{jane}->{tel_no}';
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as the string "config->{jane}->{tel_no}" was not correctly terminated. Anyway, here is my first pass, please let me know if this helps/does not help. (I whimped out and used recursion. *Smiles*)

package xmlutil;

#-- Use modules
use strict;
use XML::Simple;


#-- Define constants
use constant DEBUG    => 1;
use constant DELIM    => ',';

use constant XMLFILE  => './galaxy.xml';


#-- Define global variables
my $gConfig = XMLin(XMLFILE);


#-- This is the sub which is used to interface to the 
#-- main perl code. Had to do this as the C program does not
#-- know $gConfig
sub get_ival 
{

  #-- Get parameter
  my $pParm=shift;

  #-- Return the value
  print get_ivnode(\$gConfig,$pParm);

}


#-- This is the sub which recursively processes the XML hash array
sub get_ivnode
{

  #-- Get parameters
  my $pPtr=shift;
  my @pParm = split(DELIM,shift);

  #-- Define local variables
  my $lKey;
  my $lNewPtr;

  #-- Get the next key
  $lKey=shift(@pParm);

  #-- Display debugging information
  print '[',$lKey,']',"\n" if DEBUG;

  #-- Return the value if there are no further keys
  return $$pPtr unless $lKey;

  #-- Build the new pointer
  $lNewPtr=$$pPtr->{$lKey};

  #-- Call with next node
  return get_ivnode(\$lNewPtr,join(DELIM,@pParm));

}
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The code I used to test was:

use strict;

use lib '/temp';
use xmlutil;

xmlutil::get_ival('jane,tel_num');
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Notice this "solution" requires you to change how you are calling the perl code -- instead of building the "perlish" string, you list the hierarchy separated by commas.

Am I off base here, or is this what you wanted?

Update:

Might want to change the following line so the recursive sub is called one time fewer.

  return $$pPtr unless $lKey;

  return $$pPtr->{$lKey} unless $pParm[0];
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