The "Mount Points" screen appears only after the "Disk Partitioning" screen and is not a part of "assisted" configuration.
This screen asks you to map your disk partitions to their corresponding mount point in the files system. Each partition will need a mount point and a file system. For example, a simple configuration (root and swap partitions) would enter this at the prompts:
For each of the found partitions, specify the mount point in the system:
notes:
- 'none' will skip the current partition
- /boot should exist on ext2 or ext3 due to a bug in grub
/dev/hda1 128 MB
\_ mount point> /boot
\_ file system> ext3
\_ format> y
/dev/hda2 256 MB
\_ Configuring as Swap
/dev/hda3 9216 MB
\_ mount point> /
\_ file system> xfs
\_ format> y