how can running x86 code inside 64-bits process?

[mldonkey]

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`

[Mecanik]

That is a good question, an example for the less experienced would be nice.