How to extract raw ext3 inode data from disk?

On an ext3 (or ext2/4, pick your flavor) filesystem, how would one extract raw byte data that corresponds to a particular inode directly from the hard drive? Is it possible given, say, an inode number to determine its location on disk (perhaps as an offset from the start of the partition, or some other LBA offset) and then use some utility such as dd or a system call (something like lseek except operating on the filesystem?) to read that data without having to reference it as a file? I'm assuming this can be done, perhaps with some sort of driver-level utility.