Drug testing to be prescribed ADHD meds in AU; how to cheese it?

Cheesing a piss test: how?

I live in the wonderful country known as Australia. Been diagnosed with moderate ADHD. But to get prescribed I must undergo a drug test and be COMPLETELY clean to get prescribed. We're not too far from finally getting horse-drawn carts and steam locomotives. But, one thing we haven't advanced is prescribing ADHD meds.

Because I consume a fair bit of the devil's lettuce, my urine must look similar to the bus driver's sample from that episode of the Simpsons.

I've no idea what to expect going in there. Are they gonna watch me with cameras to ensure I don't smuggle a bottle of clean piss with me? Or is it completely unsupervised?

Any suggestions are whalecum.