Is the Vb.net dll your project? If it is, then look up "Com Interop" in help
or search this group. If not, did the author design it for com interop? If
so, then you just need to register it. If not, then I think you are out of
luck.
Implement a COM interface in the VB.Net dll , register the dll on the
target system ( with a installer or Regasm NO NOT with regsvr32.exe ) ,
and you can rerence it as anny other COM component from VB6