Yes, you will need to ship both DLLs, HEI_PAS.DLL is only an interface DLL to the actual APIs in HEI32_3.DLL.
The problem with Querying for remotely located ECOMs is that the HEIQueryxxx() APIs use broadcast packets to do the work, and internet-aware routers/bridges/swtches don't forward broadcasts.
As you've no doubt figured out, all the HEIQuery APIS are doing is finding all of the ECOMs and creating HEIDevice structures for all of the ones it finds. So, all that you will need to do is manually create an HEIDevice structure for the target ECOM and use HEIOpen with your manually created structure.
Here's a chunk of code from a VB6 application that pokes the data into an HEIDevice structure:
' If you'd rather not query the network for Host Ethernet devices, you can manually place the
' the required Ethernet information in the HEIDevice structure then call PASCAL_HEIOpenDevice
' just as you would after a query operation. The key is getting the required information into
' the correct places in the structure. Refer to the following example:
'
' aDevices(X).Address(0) = 2 ' Family= AF_INET
' aDevices(X).Address(1) = 0
' aDevices(X).Address(2) = &H70 ' ECOMs use Port number 7070(Hex)
' aDevices(X).Address(3) = &H70
' aDevices(X).Address(4) = 192 ' IP Address of the ECOM is 192.168.26.100
' aDevices(X).Address(5) = 168
' aDevices(X).Address(6) = 26
' aDevices(X).Address(7) = 100