Do i have to register a DLL to use it in Excel?

问题:

An older product we use has a 32-bit DLL that does Deflate compress/decompress. We import it in VBA thus:

Declare PtrSafe Function EtUnCompress Lib "CompPl32.dll" (ByVal SrcSt$, 
                                                          ByVal SrcLen As Long, 
                                                          Dest As Any, 
                                                          ByVal DestLen As Long) As Long

Some of our customers have 64-bit Office, so that's a problem. I was able to write my own 64-bit version using System.IO.Compression, with surprising ease.

Now the question

If I were to name my version CompPl32.dll and put it in System32, is that enough?

Or does my version have to be registered to work in Excel VBA?

I have 32-bit Office so I can't test this.