Currently no, but the work on MODx 2.x, aka Revolution, was done to abstract the database access layer so MODx could be ported to other database engines, and MSSQL is on top of our list of priority targets after MODx 2.0.0 is released for general availability.
Could you help me, if it’s possible to install MODx with MSSQL?
There will be news in the not-too-distant future regarding this; it is under development.
Any new information on this?