[rancid] Setting $OLDTIME per RANCID group or device

[Justin Shore]

I have a need to define $OLDTIME (or disabling the feature) per group or 
individual device.  I have a number of unreliable remote sites (owner 
residences, roving demo kits, etc) that are only up occasionally.  I'd 
like to not get the alerts from RANCID for just those particular device 
or the RANCID group that the devices belong to.  Is there an easy way to 
do this?  If it helps, I poll individual groups with rancid-run rather 
than simply running rancid-run with no arguments.  ie,

0 */1 * * * rancid-run abc
0 */1 * * * rancid-run def
0 */1 * * * rancid-run remote

Can I simply define $OLDTIME on the CLI in my crontab on the specific 
crontab entries that need to be changed and then let the default OLDTIME 
in the config file take over to all the other entries?

Thanks
  Justin