So I downloaded this "dmi_weap_inf_medkit" this is a bacta injector what do I need to put in an odf. to make it work
and which stock side is this in because it is a panadimic asset

I don't think it's a Pandemic asset. You just have to put "dmi_weap_inf_medkit" to the WEAPONCLASS section of the unit class you want to add it to in your custom side folder. Be sure that you have all needed odf and msh files in the correct folders (If there were any included). I can't tell much more without seeing the actual odf.