From your original post you make it seem like you are looking to test them "just because", not because you have a fault related to them. If that was not your intent, I apologize.
The CR cars monitor the glow plugs in the same way, and can be tested in the same way (and you needn't remove them from the engine to test them, in either engine).
However, the CR engines' plugs also have a cylinder pressure sensor in them, which means getting to the contact for the heating element portion will be a little trickier. Personally, I have only ever seen a couple CR engines' plugs fail in this manner anyway (and I [used to] service a lot of these). It is much more common to have the pressure sensor fail OR the connector to them have a bad contact. In which case, monitoring the pressure values while wiggling the connectors (there is a TSB for this) is how you would determine if you need a new plug or splice in a new connector assembly.
To be honest, from what I have seen, you are FAR more likely to have the intake position sensor, DPF, turbocharger, or one of the exhaust/EGR pressure sensors fail before you'll have to worry about a glow plug.
