Power off router.
Set PC nic to 192.168.1.10
Connect pc to a switch port on router.
'cd' into the same directory that you have the image file.
Run 'tftp'

tftp
(to) 192.168.1.1
tftp> binary
tftp> rexmt 1
tftp> timeout 60
tftp> trace
tftp> put image_name_here

Power on router.
Wait.
If you have problems try setting the pc's nic to half duplex 10mb