How to use only the uploaded file for I-TASSER?

I have a PDB-format file for a template structure (one that is not in PDB) that I want to use to build a homology model. It was suggested that I use I-Tasser. I pasted in the sequence I want to model and uploaded the PDB file. However I-Tasser seems to produce results only for sequences already in PDB. How can I get it to use only the uploaded file?

Thanks!