The options that control the jQuery Cycle plugin which powers the slideshows are set in the slideshow.js file. You can copy this file into your theme to override the default script and customize the options of jQuery Cycle without hacking the plugin.
Adding a custom slideshow script
Copy slideshow.js from /meteor-slides/js/ to your theme’s directory to replace the plugin’s default slideshow script.
Using the slideshow script
For ideas on how you could use this script, check out jQuery Cycle’s list of demos.