VB - Linking a DLL in implicit way

Solution 1:

Create an IDL file for your DLL that describes your exported functions in a moduleclause.

Compile with the MIDL compiler and reference the resulting tlb file from your VB6 project (Project - References).
And remove all Declare Functions.

The tlb file is only used for compilation (in this case), you don't have to include it into the setup.

Solution 2:

Here is a sample IDL that import functions from standard OS dlls

[
  uuid(YOURTYPE-LIBG-UIDH-ERE0-000000000000),
  version(1.0),
  helpstring ("My Type Library 1.0")
]
library MyTypeLib
{
    importlib("stdole2.tlb");

    typedef struct {
        long    Data1;
        short   Data2;
        short   Data3;
        BYTE    Data4[8];
    } VBGUID;

    typedef VBGUID CLSID;

    [dllname("OLEAUT32")]
    module OleAut32
    {
        [entry("SysAllocString")]
        BSTR SysAllocString([in] long lpStr);
        ...
    };

    [dllname("USER32")]
    module User32
    {
        [entry("RegisterClipboardFormatA")]
        UINT RegisterClipboardFormat([in] LPSTR lpszFormat);
        [entry("FillRect")]
        DWORD FillRect([in] DWORD hDC, [in] int lpRect, [in] DWORD hBrush);
        ...
    };

    [dllname("BOGUS")]
    module Strings
    {
        const LPSTR CLSID_DsQuery = "{8A23E65E-31C2-11D0-891C-00A024AB2DBB}";
        const LPSTR CLSID_DsFindObjects = "{83EE3FE1-57D9-11D0-B932-00A024AB2DBB}";
        ...
    }
}