As @trn notes above, the BigFix platform does allow you to write your own Fixlets.
As @cjwolford adroitly observed, the patch binaries will need to be manually cached on your BigFix server in order to “action” them.
As @JasonWalker mentions, the BigFix Services team will have an offering for Windows 2008 Fixlets to compliment the Microsoft Custom Support Agreement that provides the patch binaries and supporting documentation. We had similar offerings for Windows 2000, Windows XP and Windows 2003 End of Life events. You will need to maintain the MS CSU in order to get the binaries, our Fixlet service only produces the Fixlets that apply the MS custom binaries.
We are planning a Windows 2008 version of this paid services program for those who will be interested.