Maybe I am missing something obvious, but why wouldn't something like this work?

my @hashloc = qw{ depTar name };
my $xml = { 'depTar' => { 'name' => 'c_p20', 'loc' => 'srvr1' }};
print $xml->{ $hashloc[0] }{ $hashloc[1] };
[download]

If no, then I think that you need to give more information about what the actual user input is going to look like, and why.