If /dev/hda1 is the device on which to resize the partition:
View the current partition table to determine the minor number of the partition to resize as well as the start and end points for the partition:
To resize the partition, use the resize command followed by the minor number for the partition, the starting place in megabytes, and the end place in megabytes. For example:
resize 3 1024 2048
NOTE: Some systems will display the information as :
NUMBER START END AND SO ON...In this case, (to resize from 40GB to 20GB) type:
10 32kB 40GB HFS+
resize 10 32kB 20GB
After resizing the partition, use the print command to confirm that the partition has been resized correctly, is the correct partition type, and is the correct file system type.
After rebooting the system into normal mode, use the command df to make sure the partition was mounted and is recognized with the new size.
NOTE: NTFS gives an error message
No Implementation: Support for opening ntfs file systems is not implemented yet.
Sorry, I haven't discovered a solution to this yet.