I did a quick check on this, and this is the first thing I came up with:

"Mercury also forms insoluble mercury selenide, thus removing the selenium which could normally act as a co-factor for scavenging of hydrogen peroxide and lipid peroxides by glutathione peroxidase."

http://www.benbest.com/health/mercury.html

I have never heard of selenium described as a mercury chelator by any scientifically rigorous source, whether it be Cutler or otherwise. So I tend to think that it won't act like one. I'd probably have to break out the Merck Index or do some digging to see exactly what metals they mean.

What is kind of interesting is that Andy mentioned citrate salts as being a very mild chelator. It would make sense then, I think, to try to take calcium and magnesium in the citrate form in preference to most other forms. I take calcium ascorbate for my Vitamin C, so I have that covered, but magnesium and zinc I take in citrate form.

Now here's a question for you or anyone: What form is mercury in when it is sweated out by the body? And would the body be more likely to sweat out mercury during a round, while the body has DMSA, ALA, and/or DMPS circulating through it?