I don't think displaying the progress window for scheduled scans is possible for Macs (nothing I've heard of before, nor could I find any documents about it). My best suggestion would be to monitor navx (the process for scheduled scans) in Activity Monitor. If it's not running, there's no scheduled scan going on. Not quite the same as a progress bar, I know.
Unfortunately there are no scan logs for the Mac clients, though risks that are detected are reported (in the client UI and to the SEPM, if managed): http://www.symantec.com/docs/TECH158024
If you need to document what's being touched during the scan, you can use DTrace (command line) or Xcode's Instruments: http://www.symantec.com/docs/TECH145293
If you're concerned about high CPU usage by navx: http://www.symantec.com/docs/TECH140574
Hope this helps.
sandra