how can running x86 code inside 64-bits process?

how to use this macro?can you give a sample?
`X86_Start MACRO
	LOCAL  xx, rt
	call   $+5
	xx     equ $
	mov    dword ptr [rsp + 4], 23h
	add    dword ptr [rsp], rt - xx
	retf
	rt:
ENDM

X86_End MACRO
	db 6Ah, 33h			; push  33h
	db 0E8h, 0, 0, 0, 0		; call  $+5
	db 83h, 4, 24h, 5		; add   dword ptr [esp], 5
	db 0CBh				; retf
ENDM`