Amazing project. You will need a good meter and keep following you wiring from the fuse box to the control console. connect one probe to ground, anywhere to the car body metal. Then with the other probe you will now be able to see the 12V+ hot. You can also directly connect power to the motor ,drive to see if it runs. Maybe you can find an electrical drawing of your Volvo on the internet: https://duckduckgo.com/?q=volvo+2005+S60+elecrical+drawing&t=newext&atb=v486-1&ia=web
if you are not electrical talented, find an electrician or technician to help you to isolate the roof control in the main wiring.

we had the same, needed a 2nd key, only dealership in Mexico, 8000 pesos, about $450