I have your sanibel-ppt, but unfortunately not the -98 paper directly available. Which charges are to be determined at the HF/6-31G* level of theory? (i.e. Mulliken, (R)ESP or other population analysis?

As for new/refined parameters, I've almost completed a set of higher valency metal ions which seems to perform well and follows a physically sound parameterization routine. Will send them to you when finally tested.