In the ZDaemon console, type: snd_listmididevices
It'll list all the midi devices ZDaemon detects, each with a corresponding number.
You'll want to switch it around to your sound card, so type the following:

snd_mididevice #
where # is the number for your desired device.
Note that the devices can have negative numbers; -1 or -2 are acceptable.

Hope that helped,
gollum