Hi,
Thanks for posting!
At the moment, this isn't possible with the Ignore attribute. Tests marked with this attribute are completely invisible to NCrunch. There is a task in the backlog to make tests with ExplicitAttribute manual only, although I can't promise at this stage when this will be implemented.
The best I can suggest for the time being is to create your own ignore attribute by using a custom category, i.e. [Category("Ignore")]. You can then configure the NCrunch engine modes to avoid executing the test automatically.
Cheers,
Remco