Go into the postbit (and/or postbit_legacy) template and add this where you want to add your stuff:
Code:
$template_hook[postbit_junk]
Then, create a template with all the 'junk' you want to add in that area. Make sure your html is correct for that area. Let's say the template is called "postbit_extras".
Now, create a plugin at "postbit_display_complete" and put in:
Code:
eval('$template_hook[postbit_junk] .= " ' . fetch_template('postbit_extras') . '";');
I think that should do it (except for the plugin you make that spits out the variables you may want to use in "postbit_junk").