Building a custom Plugin

I was following an example in "Squeak Open Personal Computing and Multimedia" to make a really simple plugin.

InterpreterPlugin subclass: #ExamplePlugin

with one method:

ExamplePlugin class>>answerSeventeen

        self export: true.
        interpreterProxy
                pop: 1
                thenPush: (interpreterProxy integerObjectOf: 17)

The calling code is:
PluginUser>>usePluginPrimitive

        <primitive: 'answerSeventeen' module: 'ExamplePlugin'>
        ^ ExamplePlugin doPrimitive: 'answerSeventeen'.

I translate with no problem with:
  ExamplePlugin translateInDirectory: FileDirectory default doInlining: true.

n.b. I chose true for doInlining: on the outcome of a game of rock-paper-scissors, not really sure what the tradeoffs are here

Now here's where, several tutorials and dozens of web pages later, things get... a little murky...

InterpreterSupportCode writeMacSourceFiles.
Oh boy, this class doesn't seem to exist in Pharo or Squeak trunk even though it is mentioned by the tutorials.

Well, I read something about platform files somewhere, let's get those working:
svn checkout http://squeakvm.org/svn/squeak/trunk/platforms/

Llet's try to compile it.  Let's see what the tutorials have to say... uh oh, one uses a 3rd-party IDE and the other two finish, to trumpets, with a version of "Now, compile it to generate the library.  Bye-bye."

C compiling a little rusty
<begin flopping around here>
gcc -I~/Squeak/platform ExamplePlugin.c
doh!
gcc -I/Users/sean/Squeak/platforms/Cross/vm/ ExamplePlugin.c
oops!
gcc -I/Users/sean/Squeak/platforms/Cross/vm/ -I/Users/sean/Squeak/platforms/Mac OS/vm/ ExamplePlugin.c
nope...
gcc -I/Users/sean/Squeak/platforms/Cross/vm/ -I/Users/sean/Squeak/platforms/Mac\ OS/vm/ ExamplePlugin.c
hmm....
gcc -I/Users/sean/Squeak/platforms/Cross/vm/ -I/Users/sean/Squeak/platforms/Mac\ OS/vm/ -I/Users/sean/Squeak/platforms/Mac\ OS/vm/Developer/ ExamplePlugin.c
I'm glad my mother's not watching...
gcc -I/Users/sean/Squeak/platforms/Cross/vm/ -I/Users/sean/Squeak/platforms/Mac\ OS/vm/ -I/Users/sean/Squeak/platforms/Mac\ OS/vm/Developer/ ExamplePlugin.c
maybe I should start a new career...
gcc -bundle -I/Users/sean/Squeak/platforms/Cross/vm/ -I/Users/sean/Squeak/platforms/Mac\ OS/vm/ -I/Users/sean/Squeak/platforms/Mac\ OS/vm/Developer/ ExamplePlugin.c
...snip...
gcc -bundle -framework Carbon -I/Developer/SDKs/MacOSX10.6.sdk/Developer/Headers/FlatCarbon/ -I/Users/sean/Squeak/platforms/Cross/vm/ -I/Users/sean/Squeak/platforms/Mac\ OS/vm/ -I/Users/sean/Squeak/platforms/Mac\ OS/vm/Developer/ -o ExamplePlugin.bundle ExamplePlugin.c
<end flopping around>

Well, it created *something*

So I moved it into the VM's Resources folder with the other plugins, shut down the image, restarted, and... no go, still executing the "primitive failed" code.

I may be missing something really simple here and forgive me if this is incoherent - my brain is fried...

Where did I go wrong?  And, what should I do now?

Thanks.
Sean

p.s. I used VMMakerTool "External Plugins" button, but it just put my .c file in a different folder and created this file:

plugins.ext:
# Automatically generated makefile include for external plugins
EXTERNAL_PLUGINS = ExamplePlugin