  We develop two schemes for tuning the scattering length on the ground triplet
state of Cs_2. First, an absolute value of the triplet scattering length of
^{133}Cs_2 is determined using the experimental data (Fioretti et al,
Eur.Phys.J. 5, 389 (1999)). We demonstrate that the large scattering length can
be made small and positive by coupling of the ^3\Sigma_u^+ (6S + 6S) potential
to the ^3\Pi_g state by strong off-resonant radiation. A weaker laser field
coupling the ^3\Sigma_u^+ (6S + 6S) continuum to the lowest bound level of the
excited ^3\Sigma_g^+ (6S + 6P) also leads to a small positive scattering
length. In addition, the scattering length of the ^{135}Cs isotope is found to
be positive. The method used solves the Schroedinger equation for two
electronic states coupled by an electromagnetic field with approximations
employed. The scattering length is determined from calculated continuum
wavefunctions of low energy.
