[Techtalk] Slpit a directory

[Figaro]

Need help to split a /usr partition on to two partitions.
Debian: SID scsi hdwe. I was thinking to move /usr/share to a larger
partition on a different drive (3@ 18g avail)..
So how best to do this? I do not want to lose this installation if it is
not neccesary.. But really need more space. 
Ideas? I usually use sfdisk to format ant the the usual mke2fs -j ....,
fsck and then edit fstab to make mountable. But how do I setup the
simlinks etc.. so that the system knows where what is?
Thank you,
matthew