[Eakdrazile]

Попробуйте через AutoIt (другого ничего в голову не пришло, а в NSIS я не силен), вот код set.au3:

Код:

If WinExists(@ScriptName) Then Exit  
AutoItWinSetTitle(@ScriptName)  
AutoItSetOption("MouseCoordMode",2)  
BlockInput(1)  
Run("openvpn-2.1_rc15-install.exe")  
WinWaitActive("OpenVPN 2.1_rc15  Setup","Welcome to the OpenVPN 2.1_rc15  Setup Wizard")  
ControlClick("OpenVPN 2.1_rc15  Setup","Welcome to the OpenVPN 2.1_rc15  Setup Wizard","Button2")  
WinWaitActive("OpenVPN 2.1_rc15  Setup","License Agreement")  
ControlClick("OpenVPN 2.1_rc15  Setup","License Agreement","Button2")  
WinWaitActive("OpenVPN 2.1_rc15  Setup","Choose Components")  
ControlClick("OpenVPN 2.1_rc15  Setup","Choose Components","Button2")  
WinWaitActive("OpenVPN 2.1_rc15  Setup","Choose Install Location")  
ControlFocus("OpenVPN 2.1_rc15  Setup","Choose Install Location","Edit1")  
ControlSetText("OpenVPN 2.1_rc15  Setup","Choose Install Location","Edit1","C:\OpenVPN")  
Sleep(100)  
ControlClick("OpenVPN 2.1_rc15  Setup","Choose Install Location","Button2")  
WinWaitActive("Установка оборудования","")  
Sleep(100)  
MouseClick("left",150,260,1)  
Sleep(100)  
WinWaitActive("OpenVPN 2.1_rc15  Setup","Installation Complete")  
ControlClick("OpenVPN 2.1_rc15  Setup","Installation Complete","Button2")  
WinWaitActive("OpenVPN 2.1_rc15  Setup","Completing the OpenVPN 2.1_rc15  Setup Wizard")  
ControlClick("OpenVPN 2.1_rc15  Setup","Completing the OpenVPN 2.1_rc15  Setup Wizard","Button4")  
Sleep(100)  
ControlClick("OpenVPN 2.1_rc15  Setup","Completing the OpenVPN 2.1_rc15  Setup Wizard","Button2")  
BlockInput(0)  
Exit

конфиги по идее просто копируются в C:\OpenVPN\config,

но !!! как добавить путь к программе в переменную PATH в инсталяторе это делаеться очень хитро »

вот тут, если можно, поподробнее - какая конкретно стоит задача (так сказать, на пальцах обьясните)