Maybe some code like this

SELECT FirstName, LastName

FROM(

SELECT FirstName,

ROW_NUMBER() OVER(ORDER BY FirstName) rn

FROM( SELECT DISTINCT FirstName FROM MyTable)x) a

JOIN (

SELECT LastName,

ROW_NUMBER() OVER(ORDER BY LastName DESC) rn

FROM( SELECT DISTINCT LastName FROM MyTable)y ) b ON a.rn = b.rn