[modeller_usage] How to introduce a covalent bond in a model?

Hello, I want to link N-end of the chain alpha with C-end of the chain beta in my peptide. Terminal acids are quite near to each other (4 A), thus it is possible. I have made up some workarounds like switching the chains in pdb and seq files before making the alignment for modeller etc.; I dont like it though. I suggest that there should be some universal function built-in modeller for this kind of purpose. Do you know how to manage this?

Thank you. I appreciate your help. SDA