If you check the screenshot HERE it shows CFW2OFW Helper downloading the PKG patches before processing them, so as far as I'm aware it would require an Internet connection to do that.
There is a chart HERE for which PS3 models can be downgraded and jailbroken, for SuperSlim it can't be downgraded with a hardware flasher or jailbroken to run CFW yet unfortunately.
Your remaining options are an ODE (Optical Drive Emulator) hardware mod (not recommended as Cobra's site team-cobra-ode.com has been offline for months and unlikely to return) or the methods I mentioned HERE.
There are rumors that work is being done on the SuperSlim but currently nothing is public... it's almost easier to sell/swap it for an older model PS3 that allows installing CFW on at the moment.