R help - Mar 2010 - testing hipotheses using GAMLSS package

Hi all.
  In a GLM in which g(mu) = b0 + b1X1 + b2X2 + b3X3 + b4X4 + b5X5 + b6X6 + b7X7,
if I want to test if b1 + b5 = b2 + b6, I can use the contrast package or
multicomp package. How can I do a similar test if I am fitting a GAMLSS using
the gamlss package? Thank you for your help. Gustavo