Emtel also offers an wireless usb stick access, but I have no idea if they do that also to foreigners. That stick itself cost about 5400 Rupees and I have no idea if this is an deposit or if you have to buy it.
Maybe you check this here:
Or check with orange.mu if they can give you some infos about some hotspots.
Have you asked in your hotel if they have access and for which prize? I know Sugar Beach Resort should be around 8 Euro an hour (but am not sure)
Touessrok is free.
I can share what you said about Internet Cafes. I know two, one in Flic en Flac which is a bloody oven the other one in Rose Hill is a darn fridge (but pretty cheap), and they offer to connect the laptop.