Nope, can't do that.
But you could do something similar wth SELECT.

Code:
SELECT CASE Index
    CASE 0 : @   OutputPort pair0
    CASE 1 : @   OutputPort pair1
    CASE 2 : @   OutputPort pair2
    CASE 3 : @   OutputPort pair3
END SELECT

;-------------------------------

SELECT CASE Index
    CASE 0 : @   WritePort  _Pattern, pair0
    CASE 1 : @   WritePort  _Pattern, pair1
    CASE 2 : @   WritePort  _Pattern, pair2
    CASE 3 : @   WritePort  _Pattern, pair3
END SELECT