I can FastBoot my device. How can I reinstall an Android image to it? I accidentally deleted a file from my phone (Sky iVega IM-A800s, Gingerbread) and phone cannot boot now. I'm seeing an "System operating error" and device restarts repeatedly. 

I could get into FastBoot mode and I installed Android USB driver and ADB drivers, although I don't know what they are exactly. 

I couldn't find OEM Android images for the device (it's a Korean web site and they have an ActiveX based installer that doesn't work). 

I know StackExchange is a Q&amp;A site and I really love this site. I would like to know if you know any software that let's me install a custom ROM (I could download a custom ROM for a similar model) using the PC. 
Device does not have USB debug mode enabled and the current installation is no longer functional. Can I install a ROM (or Flash ?) using a PC (Windows/Linux) to a FastBoot enabled device?

I would be so grateful if you could shed a light for me. 

Thanks in advance.
If you can find a ROM on a forum or website, you can easily flash it using fastboot - as long as it supports fastboot flashing.

Most ROM makers provide both types of ROM flashing mode.

To flash, you should have a .img file (most likely called system.img). You can flash this  by connecting your device in fastboot mode to your pc and using this command:

fastboot flash system C:\path\to\system.img

This will then flash the image to your phone. Once that is done, erase your user data using the fastboot -w command.

You should then be able to use your phone with the new ROM, and it should boot correctly.