Thank you for the answer! I thought all Keithley 20xx were supported, since they are quite common and for basic functionality you can do a lot of re-use.
In theory, maybe. But every single device has a *IDN? response. Every *IDN? response needs to be defined for TC to recognize a device with its specific *IDN. Sometimes, that *IDN? response needs to be edited to be useful (you can see examples of this if you download TC and peruse the device definition driver files).
Typically, it's something like:
Manufacturer,Model,Serial,Firmware
All TC needs is:
Manufacturer,Model,
This is an example from the driver I'm currently working in:
#idString Batronix,Magnova,
#name Batronix Magnova
#handle Magnova
You can edit the K2000 file with the correct info from your K2001, and save it as a new file to test it out. It gets a little trickier if there are multiple versions of a device, then you need to learn about #meta and #metadef and replacetext and stuff to coordinate that. So, make your own file just for the K2001 and keep it simple to start with.

Thanks,
Josh
ETA/PS. If you have two devices with the same *IDN? response, but one has a weird prefix, you can edit out the prefix so they'd be functionally the same.