Yeah, not too hard.
Add dofile(path to Infected AI Engine file) as the first line of your LevelSetup(). You can then call any functions from Infected AI Engine.lua in your level with impunity. The path section may/will need updating, depending on where you save the AI, but that is all.
And example level may say:
function LevelSetup()
dofile("C:/Infected AI Engine.lua")
{[add roids here]}
AIinit()
end
function LevelLogic()
{[blahblahblahblah]}
InfectedAIEngine()
end
It's a lot simpler to look at, you know from the code it uses IAI and you don't need to copy the engine across. It could do with a little tweaking to prevent problems like the filepath being incorrect, but that can be fixed by changing the path...