General scripting DFM using dmctl is not supported. However, from time to time, there are procedures used for troubleshooting and working around bugs which involve dmctl.
We do offer some pre-canned scripts, though, which can accomplish bulk manage and unmanage tasks. Those scripts can be found under NMSROOT/objects/smarts/utils. They are commented, and depending on the version of DFM, you should be able to find more instructions in the DFM online help. Check under DFM > Device Management > Device Details for a link to the instructions.