Is there a way to specify Distiller job-options when converting images from FrameMaker to RoboHelp?

Hi, I am using Technical Communicator Suite 4 (RoboHelp 10 and FrameMaker 11).

I have some EPS graphics in my FrameMaker source, which have a particular Pantone colour specified (as device-independent LaB, created in Illustrator CS6).

I am using TCS4/RoboHelp to convert my Frame source to HTML Help (.CHM files).

The EPS graphics are coming out pretty awful looking (put it this way - the 8-bit on-screen preview in Frame is a better match for the intended Pantone colour than the resulting RGB PNG in the HTML Help).

In the RoboHelp settings, I have set it to use DIstiller to convert the EPS graphics, as per:

"Use Distiller to generate image

Select this option to generate web-friendly image formats from graphics linked and inserted in FrameMaker documents. You should use this option especially if you have vector graphics formats, such as EPS or AI, or graphics with text content in them. "

...but I know Distiller  should be capable of doing a better job than the rubbish I'm currently getting in my .CHMs!

How do I change the job options that Distiller is using for this conversion? As it is obviously not using very good ones by default!