From LedHed's Wiki
Prerequisites
You need a properly configured TFTP server.
Windows: TFTPD32
Linux: TFTP-HPA
FreeBSD: TFTP-HPA FreeBSD Port
Backup Command
copy running-config tftp
You will be prompted for your TFTP Server's IP address Next you will be asked for the destination filename.
Restore Command
copy tftp: <FILENAME>
You will be prompted for your TFTP Server's IP address
Next you will be asked for the destination filename. (startup-config)
or
copy tftp://192.168.150.10/my-confg system:running-config
Reference
http://www.cisco.com/en/US/products/sw/iosswrel/ps1835/products_tech_note09186a008020260d.shtml#tftp