Software/script/automator to change the desktop image periodically

Question

Hello,
Right now Mac OSX has the great feature that allows you to change the desktop image at max once a day. I would like to have an image changed once every two days. Then I would like that image to re-appear after 1 week. Then after a month. And then after 4 month.
Little more to what OS X can do.

Answer 1

I got this from this [little apple tutorial|http://www.apple.com/applescript/features/system-prefs.html]. it explains how to script system preferences (to the extent that it's scriptable).
if you run
<pre style="
font-family: Monaco, 'Courier New', Courier, monospace;
font-size: 10px;
margin: 0px;
padding: 5px;
border: 1px solid #000000;
width: 720px;
color: #000000;
background-color: #ADD8E6;
overflow: auto;"
title="this text can be pasted into the Script Editor">
tell application "System Events"
-- GET DESKTOP PICTURE SETTINGS
tell current desktop
get properties
--> returns: {display name:"Color LCD", random order:false, pictures folder:file "Mac OS X:Library:Desktop Pictures:", picture rotation:0, class:desktop, change interval:60.0, picture:file "Mac OS X:Library:Desktop Pictures:Aqua Blue.jpg"}
end tell
end tell
</pre>
it will list the properties of the current desktop and *change interval* is one of them.
you can also get it from the apple script dictionary for System Events.