The most recent ACLHelp was compiled under R5. It works on R6 and R5 - I had to make some programming changes so it was as happy on R6 as R5 because previous versions only worked on R5.
There is nothing to stop the program working on R4.5 or R4.6 in the code (in fact earlier versions worked fine on R4.6) but as it was compiled on R5 I do not think it will run on earlier versions.
So to make it work on R4.5 and R4.6 you would need to install the R4.5 C API Toolkit and recompile. It is not that hard to do, just a little time-consuming. Let me know if you need any advice or help. I'm guessing you are running on Windows?