I don't see why it would be difficult. If the concern is about legal issues in other countries then do not call it a base.
Instead you tel the pilots that there are, for ex. 50 cap/fo spots available in London. Rosters will be built from London and end in London. Pilots bid by seniority for those 'roster spots'. Your contract would be a Dubai based contract with the EXACT same pay and conditions. If you choose to take one of these 'spots' you can leave your accomodation and get the housing allowance.
You could call this a virtual basing or a roster based basing or whatever you like. The choice to actually live in London would be the pilots. He deals with any residency or tax issues himself. The keeps EK hands clean of any foreign issues.
However, if I was the co. and building these block I would also make sure that those pilots in virtual bases are clear that their block choice would be much more limited (which should be obvious). You would get the basing you like but the flying would not be nearly as enjoyable or with as many options.