Pai's counters

I've been trying to pull these off against the computer and so far it just results in me getting an ass-beating. I'd really like to get used to using them since they look so awesome but obviously there's something I'm doing wrong. I just wanted to know when you more experienced players pull these off. Can you get them off during a blocked combo? An unblocked one? Do you just use them out of the blue when you feel you can anticipate a strike?
Any help would be greatly appreciated.

Finally, I'd like to say hi to everyone. I'm new to the forums and to virtua fighter. It seems like a great game with moves that even I can pull off, emphasizing the appropriate time of using moves rather than just complicated hand maneuvers. More of a thinking man's game and I like that. Anyway, I look forward to getting to know you all. Later.

 

well, this is an OLD topic but I wonder how to use them