To allow people behind very restrictive firewalls or ISPs (i.e. just allowing http and https traffic) to enjoy our services, we have setup a separate OpenVPN instance on all our servers that is running over port 443 tcp (port assigned to https and generally allowed through all firewalls and ISPs).
You can change the protocol and port that OpenVPN connects to using the same process that you use when changing OpenVPN server (check tutorials for your operating system) and modifying the following parameters :
A word of warning about this. OpenVPN is faster and more stable when running over udp. We are providing tcp option because we like to give the maximum number of choices to our users and because some users can't use TUVPN.COM services otherwise. That said, ALWAYS use our normal OpenVPN configuration (1194/udp) when possible. If you want to get more technical on possible issues with tcp, check this thread.