since you can pass the environment configuration variables
from the munin configuration on the command line:
$ logfile=test.log sensors="0 1 7" ./munin/usb-wde1_temperature
+
+
+Permission errors
+.................
+
+ cu: open (/dev/ttyUSB0): Permission denied
+ cu: /dev/ttyUSB0: Line in use
+
+Only way that I found to fix this was change ownership of `/dev/ttyUSB0` to uucp::
+
+ $ chown uucp /dev/ttyUSB0