Extended Logical Partition in QNX6


Does anybody know how to create extended logical partitions in QNX6. I wish to have 3 Primary partition and 1 DOS extended partition with 4 logical partitions.

Alternatively, can I mount a directory on a read-only partition as a read-write mount-point. Eg. /myPrimaryPartition is a read-only partition, and can I mount /myPrimaryPartition/myRW_Arena/ as a read-write partition on /myRW_Arena