Trailing curtain sync with AF360FGZ and K100D

Hi Everyone I bought my K100D a year ago as I wanted a good camera,easy to use, reasonable price able to take low light shots without flash in the theatre - drama that is where I work for dress rehearsals. I have been really pleased with the results.
I now own a AF360FGZ flash and would like to get a bit creative and use 'trailing-curtain-shutter-sync' mode. Can anyone give me any advice on how best to set it up?. So far I have been using the P-TTL mode for my flash shots, I had a little go using the same mode but it didn't seem to work.
Many Thanks
Neil

Neil,
It's in the manual

You just slide the AF-360FGZ mode switch to the trailing curtain shutter sync - and that's it. However, it only becomes obvious when you are using a slow shutter speed on the camera. The preflash will fire before the shutter is released, the shutter will open, and just before the shutter closes the flash will fire the main flash.

Hope that helps!
Matt

Thanks Matt, that makes sense!! I did check the manual before - but guess I missed that... whoops...it says P-TTl or TTL is automatically set when the flash fires ..so I guess I'll have another go!
Thanks
Neil