frequency counts for consonant clusters in English

[M.Pettinato at city.ac.uk]

Dear colleagues, 

I am a Phd student working on the production and perception of consonant 
clusters in people with Down Syndrome.

I need to find the frequency with which certain clusters appear in spoken 
English, for example word-initial 'pl', 'str' or word-final 'lp', 'fs' etc.

Does anybody know if this data is readily available out there, or would I 
have to perform a frequency count myself?

I have been advised to use CELEX for this, but I was wondering whether it 
would also be possible to use CHILDES & how one would go about doing this.

Any ideas & comments welcome!

Michèle Pettinato