Any 12v battery and jump leads will do as long as its connected to a permanent live and earth before removing the battery.
Don't forget to insulate the main battery live wire when removed as the temporary battery will still make it live.
Same caution applies if you use a power pack.
just remember fitting a temporary memory retaining battery pack is a very short term fix. designed to keep the memory settings for a few hours normally. you will need to keep charging it up, the same as the engine battery throughout any period when the van is stood idle
I'd be wary of using a power saver or similar on a modern vehicle unless you are just changing the battery over. If you're doing any work on other systems, leaving power in the vehicle is a real risk of corrupting an ECU or could be dangerous if you're working on or disturbing the SRS system.
There's not much that needs resetting on current Ducatos. If you have the factory radio it will self reset without the need for a security code after communicating with the BCM as long as it is still in the same vehicle.