There is a sample module included to test module support.  To build
it run:

make plugtest.so

from your powwow source directory.  This will build a test plugin that
can be loaded using:

#module plugtest

If it works, when you do "#help" you will see a new command called 
"#plugtest" that is listed.  It will just echo the arguments back
to the terminal.  This is the minimum required to make a functional
module for powwow 1.2.7 and later.

Modules are loaded using the libdl interface with RTLD_LAZY so that
symbol resolution is deferred until as late as possible.  This means
that you should test any commands you create since just because a 
module loads, that doesn't mean that there are no undefined references.

The basic requirements for a module are:

1) define a cmdstruct with your command name, help text, and function to
   call
2) add your cmdstruct to the global command list via cmd_add_command in
   your powwow_init function.  You can also initialize anything else you
   need here, it will be called once at module load time.
3) perform whatever extentions you want at runtime in your custom functions

For a more complete example, you should look at the powwow-perl package
which creates the bindings from powwow using the #perl command and allows
access to powwow internals from perl via the powwow:: namespace in perl.
It also includes autoconf support and is probably the most complete
module for powwow currently.