  We develop a scheme for the extraction of the properties of the scalar mesons
$f_0(600)$, $f_0(980)$, and $a_0(980)$ from lattice QCD data. This scheme is
based on a two-channel chiral unitary approach with fully relativistic
propagators in a finite volume. In order to discuss the feasibility of finding
the mass and width of the scalar resonances, we analyze synthetic lattice data
with a fixed error assigned, and show that the framework can be indeed used for
an accurate determination of resonance pole positions in the multi-channel
scattering.
