Hi,
At first glance, there's no problem to achieve that.
You will need the Data Services side of DQM. cleansing jobs and directories. Maybe, there's a way to purchase only the directories and build your own cleansing jobs in Data Services. (You don't need the functionality of ERP; CRM; MDG and the RFC server).
These jobs could be set up as real-time services, and then, published in the web service of Data Services to be consumed by third-party applications.
--> In DS 4.2: The software supports SOAP 1.1, WSDL version 1.1, 2.0 and 2.1, and Apache Axis 1.1 (an industry-standard SOAP message handler and WSDL parser).
Check also that:
http://help.sap.com/businessobject/product_guides/sbods42/en/ds_42_integrate_en.pdf
All you need is in the chapters 2 and 3.
Regards 