I can’t give you a direct link to download the WIDCOMM stack, I’m not even sure if it’s free to download. According to Wikipedia:
Widcomm was the first Bluetooth stack for the Windows operating system. The stack was initially developed by a company named Widcomm Inc., which was acquired by Broadcom Corporation in April 2004. Broadcom continues to license the stack for inclusion with many Bluetooth-powered end-user devices.
So maybe you need a licensed Bluetooth stick to (legally) use the WIDCOMM stack…