Well I bought a class 2 dongle for 6 euri, so that won't be a big loss if I ruin it. Didn't even needed to break the case as it slid right open, I'll post pictures if this operation is sucessfull.
My plan of attack is to cut through the "antenna" integrated on the circuitboard since I don't have the schematics and the aerial is just about the only part I can clearly make out. Now I need to decide whether to try cutting it "in half" or disconnecting the whole thing first. I can probably always restore it with a bit of solder unless the transmission circuit gets fried.
If anyone has better ideas or other suggestions please let me know, as I won't get to it today anyway.