Client Won’t Include Content - Help

Greetings everyone, this is my first post here @ High Rankings. Please be gentle!

I am relatively new to SEO/SEM, and in my attempt to get my feet wet, have offered my services to a former employer for free. In return, I asked use them as a source for a referral/testimonial, and they agreed. The client is a manufacturer, with 3 websites, and probably hundreds of pages that need attention. Not a small task. For the most part, the company has followed my advice and suggestions to a T. I have spoken to them via conference call several times, and have been working along side the in-house web developer in updating their pages.

However, on one issue, I seem to be hitting a brick wall. I have stressed time and time again that there is little actual content. The web designer seems to be focused on an image-heavy site, using a flash mouse rollover script that contains important content related to their product images. As can be expected, this valuable content is not picked up by search spiders.

Can anyone offer some advice on how to convince them to change their ways?