To install ODI 11g into an Oracle 12c pluggable database, one way is to connect using a TNS string to the pluggable database service that is executing. For example when I installed my master repository, I used a JDBC URL such as;

jdbc:oracle:thin:@(DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(HOST=mydbserver)(PORT=1522)))(CONNECT_DATA=(SERVER=DEDICATED)(SERVICE_NAME=PDBORA12.US.ORACLE.COM))) 

 I used the above approach rather than the host:port:sid which is a common mechanism many users use to quickly get up and going.

Below you can see the repository creation wizard in action, I used the 11g release and simply installed the master and work repository into my pluggable database.

Be wise with your repository IDs, I simply used the default, but you should be aware that these are key in larger deployments. The database in 12c has much more tighter control on users and resources, so just getting the user creating with sufficient resource on tablespaces etc in 12c was a little more work. Once you have the repositories up and running, then the fun starts using the 12c features. More to come.