What I found in the in
openvpn.ns, that accepted parameters are:
!insertmacro SelectByParameter ${SecAddShortcutsWorkaround} SELECT_SHORTCUTS 1
!insertmacro SelectByParameter ${SecOpenVPNUserSpace} SELECT_OPENVPN 1
!insertmacro SelectByParameter ${SecService} SELECT_SERVICE 1
!insertmacro SelectByParameter ${SecTAP} SELECT_TAP 1
!insertmacro SelectByParameter ${SecOpenVPNGUI} SELECT_OPENVPNGUI 1
!insertmacro SelectByParameter ${SecFileAssociation} SELECT_ASSOCIATIONS 1
!insertmacro SelectByParameter ${SecOpenSSLUtilities} SELECT_OPENSSL_UTILITIES 1
!insertmacro SelectByParameter ${SecOpenVPNEasyRSA} SELECT_EASYRSA 0
!insertmacro SelectByParameter ${SecAddShortcuts} SELECT_SHORTCUTS 1
!insertmacro SelectByParameter ${SecLaunchGUIOnLogon} SELECT_LAUNCH 1
!insertmacro SelectByParameter ${SecLaunchGUIOnLogon0} SELECT_LAUNCH 1
!insertmacro SelectByParameter ${SecDisableSavePass} SELECT_DISABLE_SAVEPASS 0
!insertmacro SelectByParameter ${SecOpenSSLDLLs} SELECT_OPENSSLDLLS 1
!insertmacro SelectByParameter ${SecLZODLLs} SELECT_LZODLLS 1
!insertmacro SelectByParameter ${SecPKCS11DLLs} SELECT_PKCS11DLLS 1
But the parameters SELECT_PATH is not present, there is a way to add openvpn to path at install?