Hi,
According to the BI 4.1 SP01 IDT guide http://help.sap.com/businessobject/product_guides/sbo41/en/sbo41sp1_info_design_tool_en.pdf
.. XML over Web Service URLs are available now as Universe datasources.
I haven't consumed any WebSphere WS before, so not sure if that meet the required standards or not. Our products used to be very restrictive before, but now we are seeing the advent of more open sources like OData, so you might be in luck 
regards,
H