From my lecture notes it seems to be possible to derive the generators of the orthochronous proper Lorentz group
$[J_{cd}]^a_b=i(\delta^a_c\eta_{bd}-\delta^a_d\eta_{bc})$
by equaling these two expression for the transformation:
$\Lambda^a_b\simeq \delta^a_b+\omega^a_b$
$\Lambda^a_b\simeq \delta^a_b-\frac{i}{2}\omega^{cd}[J_{cd}]^a_b$
Is it right? How to do that?