Yes, depending on what exactly you want. In your plugin you will override the load_module function, which gets passed $directory and $urltoroot. It's a good idea to save these to your class. In my Markdown plugin for example, I have this:
function load_module($path, $urltoroot)
$this->path = $path;
$this->urltoroot = $urltoroot;
$path will be something like /var/www/yoursite/qa/qa-plugin/plugin_name - you can use $this->path to include any other PHP files from your plugin folder.
$urltoroot will be something like http://example.com/qa/ - you can use $this->urltoroot to output URLs for links.
One other variable is QA_INCLUDE_DIR, which points to your qa-includes directory. useful if you need to include certain files like qa-util-string.php.