Save router configuration to tftp server:

#Set copy method via OID ccCopyProtocol:
snmpset -v 2c -c  {community-string} {device-ip-address} i 1
#Set source filetype to running-config via OID ccCopySourceFileType:
snmpset -v 2c -c  {community-string} {device-ip-address} i 4
#Set destination to networkfile via OID ccCopyDestFileType:
snmpset -v 2c -c  {community-string} {device-ip-address} i 1
#Set TFTP server ip via OID ccCopyServerAddress:
snmpset -v 2c -c  {community-string} {device-ip-address} a {ip-address-tftp-server}
#Set destination filename via OID ccCopyFileName:
snmpset -v 2c -c  {community-string} {device-ip-address} s router.cfg
#Start tftp download via OID ccCopyEntryRowStatus:
snmpset -v 2c -c  {community-string} {device-ip-address} i 1

Upload router configuration from tftp server:

#Set copy method:
snmpset -v 2c -c {community-string} {device-ip-address} i 1
#Set sourcefile to network file:
snmpset -v 2c -c {community-string} {device-ip-address} i 1
#Set destination to running-config:
snmpset -v 2c -c {community-string} {device-ip-address} i 4
#Set TFTP server ip:
snmpset -v 2c -c {community-string} {device-ip-address} a {ip-address-tftp-server}
#Set desination filename:
snmpset -v 2c -c {community-string} {device-ip-address} s output.cfg
#Start tftp upload via via OID ccCopyEntryRowStatus:
snmpset -v 2c -c {community-string} {device-ip-address} i 1

Note: The integer highlighted in red is a random integer and you can choose any integer between 1 and 255. Keep in mind to use the same integer for the whole download procedure! See the integer as a session.