Can roll be controlled through elevators in a fixed-wing aircraft?
Yes. 
Fighter jets with split elevators can command a roll in the way you describe, see this answer for more info.

For an aircraft like a delta wing (tail-less) that lacks a traditional empennage these control surfaces are combined into an elevon to produce a mix use elevator aileron. 

The Concorde is a classic implementation of this design. Flying wings like the B-2 also use this design.