Speedlights w/ Cybersync's
I'm not positive on this as I've never used the flashes this way, but I think the answer is no. The 580s will only trigger other 580 flashes if one is on the camera in master mode (or with ST-E2). The one you plan to trigger with the Cybersync will essentially be a 'dumb' strobe, and will not talk to the others.
Your only options are more Cybersyncs or get some cheap optical hot shoe triggers that will pickup the other flashes.
Personally, if you are just wanting manual strobes I would look into the Yongnuo YN 560 flashes. They are basically 580 EXII flashes with all of the ETTL guts taken out. They sell new for about $80 on ebay.
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