If you read any of our papers there's always a section in the beginning that defines the language we're working in, and then defines its semantics as a translation to the lambda-calculus.
CPS is capable of expressing higher-order control-flow, for languages in which functions may be passed as values.
Instead of compiling abstract ideas of naming and control to existing hardware, as the lambda tribe did, the machine tribe took as a given the hardware available, and tries to expose the capabilities of the machine to the programmer.
The most important thing for a compiler of a machine-tribe language like C is to produce efficient machine code for loops.
But if you look at a machine-tribe language like Java, you will be dealing with many control-flow constructs that are built-in to the language (for, while, etc.) instead of layered on top of recursion like loops in Scheme.