[Dridzt]

Other idea.

local function ScrollToCategory(panelName)
  local idx
  for i,cat in ipairs(INTERFACEOPTIONS_ADDONCATEGORIES) do 
    if not cat.hidden then 
      idx=(idx or 0) + 1
      if cat.name == panelName then
        break
      end
    end 
  end
  local numbuttons = #(InterfaceOptionsFrameAddOns.buttons)
  if idx and numbuttons and idx > numbuttons then
    local btnHeight = InterfaceOptionsFrameAddOns.buttons[1]:GetHeight()
    InterfaceOptionsFrameAddOnsListScrollBar:SetValue((idx-numbuttons)*btnHeight)
  end
end

Then using as

ScrollToCategory("Skillet")

.
It might need to be called on next frame after the first InterfaceOptionsFrame_OpenToCategory("Skillet")

I'm sure someone will come up with a more elegant solution.