Can I get hold of older versions of ECLiPSe, before the open-sourcing?
No, unless you already have a license for these older versions of ECLiPSe. Before ECLiPSe was open-sourced (version 5.9 and earlier), it was available in binary form under the ECLiPSe academic license, issued by IC-Parc. The terms of this license still applies, but as IC-Parc no longer exists, new licenses under these terms can no longer be issued. Note also that sources for ECLiPSe are not available under this license.