You’ve got the first part:
1)
fdisk -l /path/to/image
to find the start offset. Take that number, multiply by 512, and you’ll get the offset option to mount. So, for sda1 in your case, 5 * 512 = 2560. Then run the mount:
mount -o loop,offset=2560 -t auto /path/to/image.dd /mount/point

Update. Actuall this way will work for both mbr and gpt drives:
—- or in case of bigger than 2tb drives. Read 1.1) —–

1.1)parted /path/to/image
must set Bytes instead of cylinders : unit B
print

lets say start is 1048576, then this should be an offset to be specified.

Seems simple enough, however I decided to create note for that.

For example, /etc/fstab has:

/dev/disk/by-id/scsi-SATA_Hitachi_HUA7230_MK0371ZZZZZZZZZ-part1 /mnt/3tb ext3 user 0 0

So, any user can mount it. But you must permit for mounted system to have permission. Lets see listing:

username@somehost:/mnt/3tb$ ls -alh
total 24K
drwxrwxr-x 3 username root 4.0K Feb 14 12:28 .
drwxr-xr-x 9 root root 4.0K Dec 27 2011 ..
drwx—— 2 root root 16K Feb 14 12:28 lost+found

The . directory (not mountpoint directy itself) should be given chmod 775 . and chown username .  for having correct permission rules.