It is possible to hardcode the E2T card without a tapi cable if you are so inclined. (don't do this unless you are certain it is necessary)
First you need to allow the system to boot with DHCP to give the E2T an address.
Then use the Secure Telnet provided by Mitel for the SX200ICP and open the E2T address on port 2000
After logging in you can use the bootChange command and follow the same instructions for the TAPI cable in the THB.
If you need more details than this, you shouldn't even be trying.
First you need to allow the system to boot with DHCP to give the E2T an address.
Then use the Secure Telnet provided by Mitel for the SX200ICP and open the E2T address on port 2000
After logging in you can use the bootChange command and follow the same instructions for the TAPI cable in the THB.
If you need more details than this, you shouldn't even be trying.