The docs do state you should use your Jenkins user token if possible, but it's much harder to automate the user setup and token retrieval, than to use a username and password setup by automated build scripts.
Sometimes, it helps to route just some traffic over a VPN. It doesn’t make sense to add a lot of latency to your vpn if you don’t need it. So here’s the magic. This only works if you have your own OpenVPN server. (See my post on using Amazon’s free tier to make it happen).
Simply comment out the redirect-gateway def1 statement in your openvpn server.conf file.
and on the client, just put in the following line:
route 126.96.36.199 255.255.255.0 vpn_gateway
Obviously this routes only the 188.8.131.52 subnet out the vpn connection and everything out your non vpn connection.