I fly through BRU fairly frequently. As I recall, as you go into the main departures hall from the tunnel (and the endless looping to get up there) there you basically make a U-Turn and go up an escalator. There are two lounges up there, with an SAS one at the end of the hall. (The other is Skyteam or OneWorld, can't remember which).

The lounge isn't bad, a tad frumpy but otherwise bog standard SAS, so not bad at all (and free wifi).