This widget will let you browse for a folder and select a playlist. Just set the root when you call BrowseForFolder.

use Win32::GUI;
use Win32::Sound;

my $folder = Win32::GUI::BrowseForFolder(
                -root => "C:\\Program Files",
                -includefiles => 1,
        );

print "Selected: $folder\n";

opendir DIR, $folder or die "Can't read $folder: $!\n";
my @files = grep{ -f "$folder\\$_" }readdir DIR;
closedir DIR;

$W = new GUI::Window(
    -title    => "Select Playlist",
    -left     => 100, 
    -top      => 100, 
    -width    => 360, 
    -height   => 210,
    -style    => 1024 | WS_BORDER | WS_CAPTION | WS_SYSMENU,
    -name     => "Window",
) or die "new Window\n";

$List1 = $W->AddListbox(
    -name => "List1",
    -left => 5,
    -top  => 5,
    -height => 155,
    -menu => 1,
    -tabstop => 1,
    -group => 1,
    -width => 100,
    -foreground => [255, 255, 255],
    -background => [64, 64, 64],
    -style => WS_VSCROLL | WS_VISIBLE | WS_CHILD,
) or die "new Listbox\n";

$List1->SendMessage(0x0195, 201, 0);
$List1->AddString($_) for sort @files;
$List1->Select(0);

$List2 = $W->AddListbox(
    -name => "List2",
    -style => WS_VSCROLL | WS_VISIBLE | WS_CHILD,
    -left => 250,
    -top  => 5,
    -height => 155,
    -menu => 2,
    -tabstop => 1,
    -group => 1, 
    -width => 100,
    -vscroll => 1,
) or die "new Listbox\n";

$Add = $W->AddButton(
    -text  => "Add >",
    -left  => 125,
    -top   => 5,
    -width => 100,
    -menu  => 3,
    -name  => "Add"
) or die "new Button";

$Add = $W->AddButton(
    -text  => "Skip",
    -left  => 125,
    -top   => 35,
    -width => 100,
    -menu  => 4,
    -name  => "Skip"
) or die "new Button";

$AddAll   = $W->AddButton(
    -text  => "All >>",
    -left  => 125,
    -top   => 65,
    -width => 100,
    -menu  => 5,
    -name  => "AddAll"
) or die "new Button";

$Remove = $W->AddButton(
    -text  => "< Remove",
    -left  => 125,
    -top   => 95,
    -width => 100,
    -menu  => 6,
    -name  => "Remove"
) or die "new Button";

$RemoveAll = $W->AddButton(
    -text  => "<< All",
    -left  => 125,
    -top   => 125,
    -width => 100,
    -menu  => 7,
    -name  => "RemoveAll"
) or die "new Button";
                             
$Close = $W->AddButton(
    -text  => "Play", 
    -left  => 250, 
    -top   => 160, 
    -width => 100,
    -name  => "Play"
) or die "new Button";


$W->Show;
$return = $W->Dialog();

sub Add_Click {
    my $sel = $List1->SelectedItem();
    if($sel != -1) {
        my $num = $List2->InsertItem($List1->GetString($sel));
        $List2->Select($num);
        $sel = -1 if $sel > $List1->Count-2;
        $List1->Select($sel+1);
    } else {
        Win32::Sound::Play("SystemDefault", SND_ASYNC);
    }
    return 1;    
}

sub Skip_Click {
    my $sel = $List1->SelectedItem() || 0;
    $sel = -1 if $sel > $List1->Count-2;
    $List1->Select($sel+1);
    return 1;    
}

sub Remove_Click {
    my $sel = $List2->SelectedItem();
    if($sel != -1) {
        $List2->RemoveItem($sel);
        $sel-- if $List2->Count <= $sel;
        $List2->Select($sel) if $sel >= 0;
    } else {
        Win32::Sound::Play("SystemDefault", SND_ASYNC);
    }
    return 1;    
}

sub AddAll_Click {
    for $i (0..$List1->Count-1) {
        $List2->InsertItem($List1->GetString($i));
    }
    $List2->Select($List2->Count-1);
    return 1;
}

sub RemoveAll_Click {
    if($List2->Count > 0) {
        $List2->Clear;
    } else {
        Win32::Sound::Play("SystemDefault", SND_ASYNC);
    }
    return 1;
}

sub Play_Click {
    for $i (0..$List2->Count-1) {
        print "Play: ", $List2->GetString($i), "\n";
    }
    return 1;
}
[download]

Thanks for the response, but I don't think I made myself very clear. This is going to be a GUI app, and it will have a box for specifying the starting directory. If, for example, someone wishes to run this app only in two specific directories:

c:\MP3s\Comedy

c:\MP3s\Oldies

If I were to use root, having descended into Comedy, I would not be able to change to Oldies.

Does anyone know if there is a way of specifying a folder without rooting to it...

Get a grip. I have shown you how to use the browse for folder widget and make another widget based on the selection. This is proof of concept not finished product. That's your job. I take it you understand how to embed widgets in widgets. Decide how you want it to work. Make a main window that supplies all the functionality you want. FWIW I would suggest Tk as it is much better documented and you will find ready made widgets quite like what you want. There are a number of GUI packages you can use, have a look and pick one that works for you.

cheers

tachyon