  We analyze the screening of a magnetic quantum dot with spin 1/2 coupled to
two helical liquids. Interestingly, we find two qualitatively different sets of
Toulouse points, i.e., nontrivial parameters for which we can solve the two
channel Kondo model exactly. This enables us to calculate the temperature and
voltage dependent Kondo screening cloud, which develops oscillations for an
applied spin voltage $\mu_s$. Such a spin voltage can be conveniently applied
by a charge bias in a four-terminal helical liquid setup.
