Is there any way to use implicit reference paths for images or other referenced drawings. If so, what is the syntax? 

In "other" programs .\\imagefolder\\ or ..\\imagefolder\\ would send you to different folders.

-p

---EDIT---

per the suggestions below, I have experimented a little. And the problem is that when I select relative path it puts the whole path in to the saved path box. and then when I open the drawing on another machine the image is not found. Nor is it showing the ../filepath/file notation

Also I have not yet found where I can change from full to relative on files that have already been attached. the ability to change over old drawings would be great.

I just tested this on all three versions mac/windows/linux v1R1.4 

I referenced an image in to the file (relative path) using each operating system that resides in the same location(relative to the cadfile)on each system.

each setup is only able to find the image it referenced in.

Then, if I open in auto cad, Acad will only find the windows file and it is using the full path to do it. If I change the paths in auto cad to be relative and then open in draftsight and all the relative paths work fine.