And Oh, You Only Need IPTABLES Command...

...to get the SNAT working.

/sbin/iptables -t nat -A CUSTOMPOSTROUTING -s 192.168.2.114 -o eth3 -j SNAT --to-source xx.x.xx.59

Where eth3 is your RED interface, 192.168.2.114 is the IP you want to changed its originating Public IP, and that xx.x.xx.59 is the Public IP you want to be used by the 192.168.2.114. Put that on console page (ssh would do).

That's all...