Redmine Ruby Rails App Install

I am having problems installing the Redmine Ruby Rails App on my cPanel Server.

I have tried installing over 4 different versions without success.
The installation fails when specific ruby gems aren't found even know they exist.

I have searched many forums and found people having the same problems.
If you want to post on a forum regarding this question then the specs of the server are here:

ruby 1.8.7.334
rubygems 1.8.15
Rails 2.3.14

*** LOCAL GEMS ***

actionmailer (2.3.5)
actionpack (2.3.5)
activerecord (2.3.5)
activeresource (2.3.5)
activesupport (2.3.5)
i18n (0.6.0, 0.4.2)
rack (1.0.1)
rails (2.3.5)
rake (0.9.2.2)
rubytree (0.8.2)

The error:
Missing these required gems:
rubytree >= 0

(Due to the rubygems 1.8.15 the command to detect this does not exist in the new version so this fails)

It appears that the latest version 1.3.0 is the only version currently compatible with our server.
However this version does not currently support rubygems 1.8.15 it only supports rubygems 1.6.2

We always keep all versions of our software up to date for security reasons so we cannot downgrade to this version.

I hope someone can help me fix this problem.

Many thanks