Showa air shock... oil question

Okay, now that I have an FSM, I see that the oil running out of my shocks upon removal was normal (if you don't know what you're doing, that is). Now I need to know if anyone here has ever refilled air shocks with damper oil? FSM doesn't give me a total capacity for the rears, but I was thinking maybe I could empty them (they will drain, but I'd rig something to compress them), and then let them suck themselves full of oil while extending them. Any reason this might be a stupid thing to try? Progressive shocks are on my list, but accomplishing this means I can ride one week earlier, and I can't tell you how ready I am to ride.

Thanks

Edit: I found the oil capacity, now just wondering what you guys think about my proposed method.

Nothing?