The program Admix can be used to compute the estimators mY of admixture coefficients from molecular data initially described in Bertorelle & Excoffier (1998) and extended to any number of parental populations by Dupanloup & Bertorelle (2001). The authors are Isabelle Dupanloup and Giorgio Bertorelle.
The web site of the last version (2.0) can be found here.
You can cite the software with: Dupanloup, I. and G. Bertorelle (2001) Inferring admixture proportions from molecular data: extension to any number of parental populations. Molecular Biology and Evolution 18: 672-675.