If I understand you right, you want to have a web site ps2.pictographic.be on 192.168.254.5, and you don't want to see the "Shared IP" page?
That's easy. Did you add 192.168.254.5 to the IP list under Management -> Server -> Settings? Then you can simply create a new web site for ps2.pictographic.be in ISPConfig, and as IP address you select 192.168.254.5.
The only problem I see is that you're in a local network, and you can forward ports from your router to only one local IP address (for example, you can forward port 80 to 192.168.254.2 or 192.168.254.5, but not to both at the same time).