Find the version you want (e.g. Wine 1.4 rather than the current 1.5), select it, go to Synaptic->Package->Lock Version.
(I don't think there's a "wine 1.4" listed, tho...)
Or - this is more likely -
Select Package (e.g. Wine), it shows version 1.5, go to Synaptic->Package->Force Version and select the version you want.
I was using wine 1.4 because 1.5 had some bugs with sliders in GUIs (e.g. clicking the volume slider foobar made the whole GUI flash obnoxiously).