Since you mentioned an IIS server, it would be very simple to throw together small ASP pages to call your "cool" routines.

Dim Obj as Object
Set Obj = CreateObject("ProgID_of_your_Perl_DLL.app")
Obj.CoolRoutine
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Update:
It was late when I first posted this so forgive me for not providing a pure Perl solution. This is PERLmonks after all and it ate at me so bad that I climbed back out of bed to add this to my post:

Once the .dll is on the server and registered properly you can call it via you Perl CGI scripts by adding:

use Win32::OLE;

my $obj = Win32::OLE->CreateObject('ProgID_of_your_Perl_DLL.app');

$obj->CoolRoutine();
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