[ccp4bb] fit a peptide in isolated density

[<Rain Field>]

In an isolated piece of density, I want to fit a 7AA peptide fragment from a 
protein.
Only the sequence of the whole protein (200AA) is known, and I don't know the 
peptide sequence.
I think it's best to try from the beginning of the whole sequence to the end.
So is there any software or scripts which can do this automatically? The 
resolution is 2.3A.
Waiting for your reply!
Thank you!