It seems "apt-get install OpenVPN" from xterm should be able to load all the dependencies. I have not tried. I was having the same problem with my N770 reporting LIBLZO1 as missing when installing GPE-Calendar, I searched everywhere for it to install it but I always got the error the package was invalid or incompatible.

In my case the solution was to re-install the latest ITOS2006 (Which was actually the same I had) that reloaded the missing library and I was able to install GPE-Calendar and other apps. In your case you can re-install the latest ITOS2007 if no other resource comes up.