I have recently started using ltk with CCL on a Mac (OS 10.6.8).  I would like to be able to use the "load-image" command to display jpeg images without having to convert them to gif or ppm.  I read on the web that 

"In order to use modern formats like PNG and JPEG you will need to install the libimg extension library for Tcl/Tk (e.g. in Ubuntu, you need to install the libtk-img  package) and require the package before you use it."

My question is, does anyone know how to install libimg on a mac so that I can "require" it from ltk? 

Thanks very much!

Melanie