CCL: Charmm Cl parameters

 Hi all,
 I have recently switched to the charmm force field from amber, and am
 interested in performing some simulations in CHCl3 and CCL4. Unfortunately
 I have been unable to find Cl parameters in Charmm and was wondering if
 such were available or if there is a methodology for converting from amber
 to charmm parameters!
 Many thanks,
 Gemma Kinsella