[Plugin: Promotion Slider] How to add timthumb to images to prevent stretching

Great slider, only one that would work for me!

I want to know how to add timthumb code to allow for the main image and thumb images to be resized and not stretch. Ive applied timthumb before in php to handle images but i can’t seem to get it to work on this plugin. Otherwise, how can i get the images to proportionally resize.

Thanks ahead for helping.

Example page: http://www.mogultheory.com/test

http://wordpress.org/extend/plugins/promotion-slider/