In kAudioCreator, there is an option to do that. Currently, each encoder is set to ~/%extension, which will automatically translate to your home directory. Go to Settings | Configure, then click the Encoder icon in the column on the left. Select each of the installed encoders and click the Configure button. Go to the beginning of the Encoded File Location text, and change the '~' to the mount point for your other partition. Do that for every encoder and you'll be all set.
In retrospect, everything is funny.
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