can anybody describe me how to install vncserver on Oracle Linux without yum?
(yum does not work because it is a pre-built appliance - timeouts all the time)
Sounds improbable - maybe you just haven't configured the repositories / not configured any routes to the repositories.
But you could just download the rpms and install them yourself (IIRC, RH, Oracle and Centos use the same version numbering, the "unbreakable" Oracle kernel is supposed to be compatible with the RH kernel). But you'll need to manage the dependencies yourself.