`L = thisComp.activeCamera;`

u = fromWorldVec(L.toWorldVec([1,0,0]));

v = fromWorldVec(L.toWorldVec([0,1,0]));

w = normalize(fromWorldVec(L.toWorldVec([0,0,1])));

sinb = clamp(w[0],-1,1);

b = Math.asin(sinb);

cosb = Math.cos(b);

if (Math.abs(cosb) > .0005){

c = -Math.atan2(v[0],u[0]);

a = -Math.atan2(w[1],w[2]);

}else{

a = (sinb < 0 ? -1 : 1)*Math.atan2(u[1],v[1]);

c = 0;

}

[radiansToDegrees(a),radiansToDegrees(b),radiansToDegrees(c)]

`or you can target a specific camera in the first line, eg `

`L = thisComp.layer("Camera 1"); `

u = fromWorldVec(L.toWorldVec([1,0,0]));

v = fromWorldVec(L.toWorldVec([0,1,0]));

w = normalize(fromWorldVec(L.toWorldVec([0,0,1])));

sinb = clamp(w[0],-1,1);

b = Math.asin(sinb);

cosb = Math.cos(b);

if (Math.abs(cosb) > .0005){

c = -Math.atan2(v[0],u[0]);

a = -Math.atan2(w[1],w[2]);

}else{

a = (sinb < 0 ? -1 : 1)*Math.atan2(u[1],v[1]);

c = 0;

}

[radiansToDegrees(a),radiansToDegrees(b),radiansToDegrees(c)]

Found at: http://forums.creativecow.net/thread/227/21917#21917