SAP ABAP Migrating test programs from ECC 4.6 to 6.0

We are currently upgrading from 4.6 to ECC 6.0; in our current DEV environment we have some dev-only and test programs that have not, and will not, be transported. How do we go about migrating them to our new ECC DEV environment which will be a copy of our latest 4.6 production environment?

It is generally considered a very bad idea to replace a development system. You lose all the history of the developments carried out, as well as useful utilities as you mention. If it is deemed absolutely necessary, despite being considered not best practice, then you can safeguard your dev/test programs by putting them into a development class/package, recorded against a transport. When you release the transport, transport files are created on the applications server, which can be later used to re-import the developments.