How can i flash a similar custom rom using standard recovery?

[AC Question]

Hello, i have an italian NGM wemove legend based on mediatek 6575 chipset. I decided to root the device, with success, but, playing wit ultimate dynamic navbar the device gets in boot loop. The problem is that i hadn't install a custom recovery (i didn't found any version compatible for my device in cwm site), so for me it's impossible to anything.
I can turn the device in factory mode (pc can recognize the device) or in recovery mode (pc can't find the right driver). Before this brick, the pc recognize the smartphone.

Looking on internet i found that my device is similar (clone) of the micromax a90, i could find a custom rom for this model, but if i put the zip file in sd card and i try with stock recover to flash it gave me error with sign validation.

I think there are few possibilities: the first i think is to have from the manufacter the original rom, so maybe the stock recovery can flash it with no error.
The second way is to flash another recovery that can skip the sifnature validation, but i think it's very hard to cause device isn't recognized well by the pc, or in factory mode i can't do nothing.

Does anyone has an idea how can i fix this problem??

Thanks in advance.

Gianni

ps. sorry for my poor english, i'm a beginer with android ;-)