The easiest thing to do is run a TFTP server on your computer and then run a copy tftp startup-config on the device while it is running as normal. Just fill in the questions asked with the correct info and it will copy the config from your PC to the startup-config file on the device.
Then, issue a reload noconfirm command on the device and it will restart and load the config you just transferred with no mucking around with copying, pasting, and formatting, and stuff like that.
Very quick, very easy, and 100% accurate.
Cheers! Let me know if you have any questions!