Yes, here's a sample script that will toggle the availability of the Errands context each time it is run:
Code:
tell application "OmniFocus"
tell front document
set idHome to id of first item of (complete "Errands" as context)
set homeContext to first item of (every context where id is idHome)
tell homeContext
set allows next action to not allows next action
end tell
end tell
end tell
Looking at the variable names, you might well deduce that I originally was toggling the state of a different context :-)