使用OD反汇编修改NateOn，虽然很麻烦，最终还是搞定了，后来发现网上有段代码，直接可以实现程序多开，测试了MSN、NateOn没问题，代码如下：
.386
.model flat, stdcall
option casemap :none
include windows.inc
include user32.inc
include kernel32.inc
includelib user32.lib
includelib kernel32.lib
PATCH_POSITION equ 00543CEEh
PATCH_BYTES equ 2
.data?
dbOldBytes db PATCH_BYTES dup (?)
stStartUp STARTUPINFO <?>
stProcInfo PROCESS_INFORMATION <?>
.const
dbPatch db 3Dh,0B7h
dbPatched db 3Dh,0B6h
szExecFilename db 'C:\\Program Files\\MSN Messenger\\msnmsgr.exe',0
szErrExec db '无法装载执行文件!',0
szErrVersion db '执行文件的版本不正确，无法修正!',0
.code
Start:
;********************************************************************
; 创建进程
;********************************************************************
invoke GetStartupInfo,addr stStartUp
invoke CreateProcess,offset szExecFilename,NULL,NULL,NULL,NULL,NORMAL_PRIORITY_CLASS or CREATE_SUSPENDED,NULL,NULL,offset stStartUp,offset stProcInfo
.if eax
;********************************************************************
; 读进程内存并验证内容是否正确
;********************************************************************
invoke ReadProcessMemory,stProcInfo.hProcess,PATCH_POSITION,addr dbOldBytes,PATCH_BYTES,NULL
.if eax
mov ax,word ptr dbOldBytes
.if ax == word ptr dbPatch
invoke WriteProcessMemory,stProcInfo.hProcess,PATCH_POSITION,addr dbPatched,PATCH_BYTES,NULL
invoke ResumeThread,stProcInfo.hThread
.else
invoke TerminateProcess,stProcInfo.hProcess,-1
invoke MessageBox,NULL,addr szErrVersion,NULL,MB_OK or MB_ICONSTOP
.endif
.endif
invoke CloseHandle,stProcInfo.hProcess
invoke CloseHandle,stProcInfo.hThread
.else
invoke MessageBox,NULL,addr szErrExec,NULL,MB_OK or MB_ICONSTOP
.endif
invoke ExitProcess,NULL
end Start