There is no such a thing
SELECT Col1, Col2 FROM EXEC MY_SP @PRM = 1
What you have to do is declare a temporary table, insert the result of the EXEC into it, than select from that temporary table...
CREATE PROC MY_SP (@PRM INT)
AS
SELECT @PRM AS ONE, 2 * @PRM AS TWO
DECLARE @RESULT TABLE (ONE INT, TWO INT)
INSERT INTO @RESULT
EXEC MY_SP @PRM = 1
SELECT ONE FROM @RESULT