Pass extra command line parametes to plink in ANT CVS task

I'm trying to make plink use the private key using the commnand line -i instead of relying on pagent in a ANT CVS task. I tried to set the cvsRsh param to "plink.exe -i my_private_key" without success. It complains that program cannot be found.

Of course i tried all sorts of quotes combination but it seems it tries to validate the path instead of just executing the cvsRsh variable.

So you have any ideas how to accomplish the same thing ?