Mac Pro how to boot in safe mode with a Windows Keyboard?

Model No: A1186

Mac Pro 3,2

I think it's a 2008 with an unknown version of MacOSX installed.

I'm stuck at the blue screen, I'm pretty sure it's a permissions problem, as I lost the network connection when setting it up. But I can't boot into safe mode. I just bought it online. I also tried to boot a Clonezilla Live CD with little luck.