Wanna Make My First Mod, Replacer For Gas Dispenser

I've never made a mod before, but I want to try to make one that replaces the Gas Dispenser for Tag Team with the Medical Syringe from Killing Floor 1.
From what I can tell, I'd need to override the name and the image(s), but I don't know where to start.
HUD Textures - Blackmarket:
HUD Texture - In-Game (it's an atlas and not independent unlike Pocket ECMs/Leech Ampule):
As for the text strings, you can use Offyerrocker's Simple Localization Mod Template to easily change them via BLT. Specifically these:
name_id = "bm_grenade_tag_team", desc_id = "bm_grenade_tag_team_desc",So, it'll look something like this:
Hooks:Add("LocalizationManagerPostInit", "KF1MedicalSyringe", function(loc) LocalizationManager:add_localized_strings({ bm_grenade_tag_team = "Medical Syringe", bm_grenade_tag_team_desc = "Cocaina, no flour.", }) end)