Mega2560 + ESP8266-07: how update firmware?

Hi All,

I have an ESP-07 functioning well with MEGA2560 - no problem in sketch access...

But I'm trying to upgrade the ESP-07 firmware using Arduino as TTL/USB interface without success.

I had read a lot of samples in Internet and none success at all. I have the Espressif PDF talking about GPIo0,2,15 and their necessary states to put ESP in "UART/FIRMWARE" mode - and I cannot access it in any way.

When I utilize Serial programs (like CoolTerm and Termite) they found the right COM port, send the command (any AT one) and they don't receive any data.

I guess I'm accessing only the Arduino because if I have any sketch there, these programs show me the answers of the sketch - not the supposed answers come from AT-command.

Abstract:
1- The module if functioning well with Arduino.

2- If I call a serial program to get, for instance, AT+GMR, I have no answer at all, even using ANY direct AT command.

3- In my sketch using Wee (ITEAD) library I can access many AT commands (I receive answers).

4- If I put the ESP-07 in "firmware mode", neither serial-apps nor the Espressif firmware app can find it.

I don't want to buy a FDTI interface just to perform ONE firmware update in ONE single ESP-07.
Do you know what can I doing wrong?

Thank you for any help.