Hi Bissona,
Before you start hacking it, I may point you out in the right direction.
I'm building a spare set of commuting wheels for my Focus Bold 2 and had the same problem of sourcing the rear rotor with the magnet. As you know the magnet is attached to the rotor (six bolt pattern) via special bracket. At first I thought that it would be a Shimano part, so I contacted them.
Shimano replied that this is a third party part made for Focus and Shimano makes the 160 or 180mm rotors with integrated magnet only in centerlock design.
So I've called an Australian Focus importer/distributor and found out that this part is stocked with Part Number 170 517 017, Bolt Pattern Magnet Holder and costs here around AUD10.00.
Unfortunately they won't sell directly to public, so I was advised to see my LBS and ask them to order it for me. So if you find out your Focus distributor, call them and see what they say.
BTW in the end I ended up not getting this holder, because the six bolt pattern wheel I was looking at initially had really bad user reviews (aluminium where steel is needed). Got a good deal on Shimano MT centerlock 12x148mm wheel. Nothing fancy, but for commuting on asphalt with 2.4" Schwalbe Super Moto X on both wheels will do just fine.
It was a bit of a gamble as the spec said that hub can take 9 and 10 speed cassette only. Found the same wheel on one of the German online shops which said 9, 10 and 11. Then of course just ordered from CRC the Shimano centerlock rotor with magnet (AUD 77.00), and 11-42 XT cassette.
Fitted it all last night, the Germans were right. No problems, all works like a charm.