[R] goodness of fitting for a mixed distribution

[nelson -]

Hi all!
  i have done a fitting of experimental data using optim function and
setting up my mixed distribution logliklehood (it is a linear
combination of a normal and a weibull distribution). How can i test
the goodness of fit? I want to be able to say that my distribution fit
the data at 90%, 95% or so on....

thanks in advance,
  nelson