The CMT kit will let you know if there is mastitis, but not the actual somatic cell count. I have Dr. Naylor's Mastitis Indicators, which are cards with four sections. You squirt milk from each quarter on a separate section and the color change indicates healthy or mastitic milk. Here's a link to them: http://www.jefferslivestock.com/ssc/product.asp?CID=2&mscssid=P2ATRMXJT5R69PC3LP258WNV2WMQ1FNA
This was very helpful for me the one time that my cow got mastitis in one quarter.
Even simpler are the instructions I found on the Keeping a Family Cow forum, courtesy of member Midgimoo:
"Also, there's the simple home-made mastitis test.
Take equal parts Dawn dish soap and raw milk from a particular quarter and swirl (don't stir) them together in a bowl or dish....there shouldn't be any geling or thickening of the mix...if it gels or thickens then you have a bacteria problem."
Members there are very specific that it has to be Dawn - other types of dish soap must not work quite the same way.