You can create a Global Blox Variable if you need a global reference to something. http://www.plyoung.com/blox-variables.html#global-variables
It is not truly a Singleton since there is no checks to make sure a duplicate of the type is being created. Blox is not a programming language like C# or C++ and you should not think on those terms when using it.
Keep in mind that Blox was not developed as a C# (or other) Code Writing tool. The code generator is just a supporting thing and not the main idea behind Blox. It did not even have a code generator for a long time and was not developed to be a code writing tool. So do not expect to find concepts you are familiar with in C# in Blox, like delegates, singletons, static, class properties, etc.
... excuse me if I have been over explaining it again and you really was just wondering about keeping references in a "global scope", I just need to make sure people reading this and trying to decide whether Blox is the tool for them understands what it is about, or not about.