Are you sure it won't work with any PCIe mini based SSD cards? This link indicates that one of your customers did, indeed, get this working: http://communities.intel.com/message/143517#143517.
It sounds like the trick is to ensure that one uses a true PCIe mini SSD that is NOT mSATA (or many of the other customized varations that have been made for Dell and Asus and other netbooks and laptops).
There is an article on the varations of PCIe mini connectors here: http://www.tomshardware.com/reviews/intel-ssd-310-msata-mini-solid-state-drive,2854-3.html and a pin-out chart here: http://www.specreport.com/mpcie/mpcie-pinouts.html.
Don't the D525MW (and D525MWV) motherboards follow the "Standard PCIe mini pinouts" or is your connector also somehow custom?
This has me curious as I purchased the D525MWV and a Wintec PCIe mini SSD only to disover the SSD would not work. My conclusion was that the SSD was "mSATA' which will not work with your motherboard, however, it sounds like using any "standard" PCIe mini SSD (like the SuperTalent in above link) should work. Your post indicates that PCIe mini SSD flat out will not work.
For others that find this old thread, I was able to find specific information on the Intel site:
Only specific motherboards have native support for mSATA on the PCIe x1 Minicard slot
Solid-state drive (SSD) compatibility
Fortunately, there are plenty of adapters, search: msata to sata adapter