It seems that you have a pretty good understanding of what you are doing. I, on the other hand, do not remember well things about legacy BOOST. But I'll try...
Oh, no, I was wrong: you are not using legacy BOOST - you posted in the wrong forum, but never mind. You are using universal BOOST. Its message in the log file "Modded game detected!" most likely indicates that ENB wrapper has successfully injected itself. So, this is OK.
If you want to use additional d3d9.dll with universal BOOST and ENB, you need just follow ENB instructions (don't worry about BOOST): rename your dll and edit ENB's file, probably enblocal.ini. Something like this
[PROXY](BTW, keep in mind that HiAlgo handles lag by itself; this is one of its major points; so the two mods very likely will interfere with each other).