If anyone is interested, I created an ACS auto-complete file for Notepad++. It works alongside Blue Shadow's syntax highlighting. You just have to put the file in the "autoCompletion" directory inside your Notepad++ installation. You also need to rename the language imported from Blue Shadow's post from "ACS (LT)" or "ACS (DK)" to just "ACS" (or rename the autocompletion file to "acs (lt).xml" or "acs (dk).xml" and change the language in the file). Note that auto-completion will only work when typing lower case if only the "function complete" option is set (i.e. it doesn't work correctly with "function and word completion", apparently that's a known bug in Notepad++).
The file is generated by an ugly-ass Python script I wrote, I guess I'll have to clean that up and put it on GitHub or something.