[Request]Scaleform base Loading Screen

Is it possible?
pre-load with fxmanifest.lua

fx_version 'elegant'
games { 'gta5' }

file 'popup_warning.gfx'
client_script "client.lua"
loadscreen_style 'scaleform'  --default 'html'
loadingscreen_scaleform_name "popup_warning"
loadscreen_manual_shutdown "yes"

scripting with client.lua like AddLoadingScreenOverlay (AddMinimapOverlay)
FiveM update - December 3rd, 2017
maybe

local LoadingScreenGFX = AddLoadingScreenOverlay('popup_warning.gfx')
--[[   or maybe just no texture load
RequestStreamedTextureDict('popup_warning')

    while (not HasLoadingScreenOverlayLoaded(overlay)) or (not HasStreamedTextureDictLoaded('popup_warning')) do
        Wait(0)
    end
]]--

    --Wait(1500)
   --[[   or maybe just no input
    CallLoadingScreenScaleformFunction(overlay, 'SHOW_POPUP_WARNING')
    PushScaleformMovieFunctionParameterFloat(500.0)
    PushScaleformMovieFunctionParameterString("ALERT")
    PushScaleformMovieFunctionParameterString("wew")
    PushScaleformMovieFunctionParameterString("~r~wtf")
    PushScaleformMovieFunctionParameterBool(true)
    PushScaleformMovieFunctionParameterInt(0)
    PopScaleformMovieFunctionVoid()
]]--

    -- overlayID, x, y, xscale, yscale, alpha
    SetLoadingScreenOverlayDisplay(LoadingScreenGFX x, y, 1.0, 1.0, 125.0)

while true do
if NetworkIsSessionStarted() then
KillScaleformLoadingScreen()
break
end   
if GetLoadingGFXResultFunctionString("FINISH_LOADING") == "ok" or GetLoadingGFXResultFunctionInt("FINISH_STATE") == 1 then 
KillScaleformLoadingScreen()
break
end 
Citizen.Wait(0)
end 

no, not likely at all, your proposal also has numerous odd flaws that make it entirely impractical