How the heck do I use a flash with this...?

[Drizzt321]

So I've recently started shooting with an old Pre-WWII Mamiya Six II/III (10x10mm waist viewfinder), it's great, but I'm trying to figure out how to use a flash with it (probably get an older, small pocketable flash). There's no pc-sync port that I see. You can find some images at Camera-Wiki, and the specific model I have has this specific lens/shutter/mount. Note, this is not mine, but I can provide images of my specific camera if needed. So, anyone shot with this style back (way back) in the day? Or will I have to cobble together my own method for triggering a flash if I want to use one with this?