Hi!
You can download Crystal Space going to
http://www.crystalspace3d.org and click on the section \"download\", if you have any trouble follow the documentation, write to the ML or contact the authors on IRC.
I would anyway want to ask you:
1) Are you alone in this project? Then, if you are, it is maybe better and easier to work ON PS. If you are skilled they need your help as well! Plus, doing such a project alone require a HUGE amount of time.
2) if you want to use PS I think you MUST understand CS and CS is not easy. Try to make an estimation of the difficulty, considering your skills.
Bye,
Ary