A lace monitor is a lace monitor, regardless of patterning. Bells aren't a different species, or sub species, they are a genetic mutation (someone correct me if I'm wrong). They can be kept successfully anywhere within the lace monitors distribution, and be treated just like a local. I have a pair of QLD lace monitors (from central coast QLD, where bells are aplenty), and I keep the male outdoors all year round (I am on the south east coast of NSW- Illawarra region). The female is kept indoors over winter, but cooled. Both do very well and can handle the cold temps. It would be the same for a Bells lace.
However, since you are in Melbourne, I do recommend some form of heating for your animal over winter. That, or bring it indoors over winter.