This really depends on how much programming they know, but I've seen R successfully introduced to people with absolutely no knowledge of programming successfully. I'm going to guess that they don't have much knowledge of programming.
This may sound obvious, but teach only as much of the language as they need to solve the problem, don't get in too deep with "proper" and efficient coding styles, you can start working this in slowly once your students have some understanding, e.g. comment on style, but don't be too strict on it.
To solve a problem you have to understand at least some basic part of the language. I'm going to assume that everything you do will likely be contained in a single line and namespacing, modules, performance, etc really won't be top priorities.
Start by getting them setup with a development environment, and create a simple program for them to run. Make sure they have an environment that has everything they need (if they need numpy, walk them through installation), walk them through starting a program from the command line, and of course have an editor that's easy to use (e.g. Eclipse + PyDev, probably too complicated). The most frustrating thing is when you can't get an working environment. Pray you don't have to support windows or don't have many libraries to contend with.
Once you have that, introduce them to the language in general. Cover types and the subtle problems one may encounter, e.g.:
>>> 1/2
0
>>> 1./2
0.5
I would even instill a habit of making everything floats. Introduce strings for output and how to cast that output if you want it on the same line. Cover operations and logic, then provide an introduction to "functions," making sure to create a distinction between the mathematical equivalent. I think command flow structures should be fairly simple and include the simple ones (if, else, elif, possibly while).
At this point they should be able to create a simple program to solve a simple problem. Start building on this, introducing more complex command flows, more complex data types (lists, sets, dicts), possibly iterators and generators (be careful with these, they can be a pain and you may not need them).
Edit:
I forgot to touch on input and output. I would provide a simple framework your students can use for this, if you want to. The command line should be sufficient unless you want to trace what's happening in which case a file output is much more reasonable. Alternatively, piping output to a file works just as well.
I think sets are much more mathematically relevant (and useful!) then dicts are, and would introduce them first.
