FreeRADIUS 1.1.2 -> 2.1.12 migration steps

All, At my new working place I have inherited a FR 1.1.3 running on CentOS 5.6. Beyond being outdated and unsupported, this FR setup is causing a lot of problems so I plan a migration to RHEL5 and FR 2.1.12. I've been searching but I cannot find a procedure describing which steps to follow in order to migrate from one server/version to another. Can someone please shed some light or point me in the right direction? TIA, Martin