Yes it is possible:
0/ Read CHARMM papers (JCC 1984 and 2009), and other relevant literature.
1/ Discuss at length with you supervisor. Repeat as necessary.
2/ Energy-minimize the structure thoroughly. Command MINImize. Use a good minimizer, ABNR or NRAPH. (minimiz.doc)
3/ Do a normal mode analysis. Command VIBRAN/DIAG. (vibran.doc)