I have not tested the RoutePath in the INI file, but it should work as long as it matches the property name exactly including casing.
If specifying something in the RoutePath, the ProcessorSlot value is ignored. The ProcessorSlot is there for simplicity, the same thing can be specified in the RoutePath with 1,x (x being slot number).
The IPAddress property is the address of the Ethernet card in the ControlLogix rack that your computer sees directly. The one that you can ping from your PC.
Example:
---Physical Network Setup---
PC on plant network with HMI :10.10.1.5
EN2T card on plant network : 10.10.1.100
EN2T card in slot 5 : 192.168.1.10
EN2T in Remote Rack : 192.168.1.11
Processor in Slot 1 of remote rack (target PLC)
---Driver property setting---
IPAddress : 10.10.1.100
RoutePath : 1,5,2,192.168.1.11,1,1
---Breakdown of RoutePath---
1a) Leave port 1 (backplane) of EN2T
1b) Enter slot 5 into second EN2T
2a) Leave port 2 (front Ethernet port)
2b) Go to link address 192.168.1.11
3a) Leave port 1 (backplane of remote rack)
3b) Enter slot 1 (processor in remote rack)