It's not possible to get the map upgrades with old TTHome. It's also not possible to modify new navcore.
Instead, the usage of two SD cards can help to get usefull upgrades without unnesessary update of the navcore.
To this end, one need to use TWO SD cards:
a) the fake SD card to which all updates can be collected and, then, transferred to the computer, and
b) the actual SD card, to which the new elements (except for the unwanted ones) can be restored from the computer.