Unfortunately the scan command from SEPM can be send either to single machines or the whole groups. Probably no way of picking up several of them and sending the command from SEPM console.
What you can do as alternative is to use the doscan.exe command:
http://www.symantec.com/docs/TECH104287
...from either command prompt or scipted and sent to specific clients.
The tool has several options:
- scanning of specific files, folders or drives only
- triggering the scheduled scans
- running quick scan