I believe you already can do that. Some examples:
<?php
# Check that function exists before trying to use it
# Just in case someone disabled the history plugin or similar
if (function_exists("simple_history_add")) {
# Log that an email has been sent
simple_history_add(array(
"object_type" => "Email",
"action" => "sent",
"object_name" => "Hi there"
));
# Will show “Plugin your_plugin_name Edited” in the history log
simple_history_add("action=edited&object_type=plugin&object_name=your_plugin_name");
# Will show the history item "Starship USS Enterprise repaired"
simple_history_add("action=repaired&object_type=Starship&object_name=USS Enterprise");
?>
Would that work for you?