You probably don't need to do it. GNU Smalltalk supports dynamic linking, and it's probably easier if you make a plug-in module instead. This is how most library bindings work.

If you are interested in how the virtual machine works, however, modifying it may be very instructive. The code is well commented.

In GNU Smalltalk, an image is used mostly as a cache of preloaded packages. In general, if you plan to use a package in a script, development will be quicker if you preload packages into your image.

Creating an image

Start GNU Smalltalk, and save a snapshot of the running system

st> ObjectMemory snapshot: 'my-image.im'

Loading a package into an image

Use the gst-load script bundled with GNU Smalltalk. For example, to load NetClients, use this:

$ gst-load --image-file=my-image.im NetClients