Hi Padelis,
Unfortunately the flash in the 9S12T64 is different to any of the currently supported devices and I don't have any similar device to test with.
Attached is a ZIP file with files you can try. I have no way of testing these - good luck.
Copy hcs12_devices.xml to C:\Program Files (x86)\pgo\USBDM 4.10.6.120\DeviceData
Copy HCS12-MMCV4-FTS_3-flash-program.s19 to C:\Program Files (x86)\pgo\USBDM 4.10.6.120\DeviceData\HCS12
The remaining files are test files to check that the flash routines work.
bye