Please make sure to point out what game system you're using when posting in this general forum. If I hadn't been discussing this with you in the WoD forum, I wouldn't have context to be able to help out. :-)
Oh, and you're welcome to post stuff like this in the WoD forum if you want, as it's of specific interest to WoD players. :-)
The first thing you need to do is create the new specialization so that a dependency can be established upon it. Go to the Specialization tab in the Editor and create it as a copy of an existing Crafts specialization, such as Painting. I'm going to assume you give it the id "zConstruct".
If you add any specialization to the character, the identity tag of that specialization is automatically forwarded up to the character. So you can easily verify whether a particular specialization is on the character by checking for that tag.
You can look at the Bishopric of Blackbirds for an example of a pre-requisite on a skill. Switching that to a specialization is easy. Copy the pre-req script and change the "validif" statement to check for the tag instead of the skill level. The new line will look like below.
Code:
validif (hero.tagis[Specialize.zConstruct)
Since you don't have to check for a skill rating with a specialization, though, there is an even easier way to do this. Click the button to add a "Pick-Req" instead of a general "Pre-Req" to your entitlement. Enter the id of your specialization (zConstruct). And save. That's all you need to do to establish a pre-req on the existence of another selection for the character.
Hope this helps!