Question [Q] How to run a custom ROM on 5830B? Keep getting assert failed on CWM

[Posting to the right forum now, sorry]

Hey guys,

I keep seeing that the 5830B is almost the same as the "raw" 5830 but for radio frequencies set; however, I´ve tried to install some custom ROMs (Slim and BlackHawk for example) and they all fail at trying to assert for a 5830. They don't mention the variant(s).
That was not a good surprise for me as I always format /system before flashing a new ROM...

Then I tried getting back to stock and found out that Winx64´s USB stack doesn´t like Sammy´s download mode, so no go trying Odin. Great!

Is there any way around this?

I I have the latest CWM recovery installed and I can dump files on the FS through USB mounting. I wouldn´t have a problem flashing a modded stock, that is flashable via CWM, but as I got so many assert failures on different ROMs I thought of asking first...
Meanwhile I'm building a Winx86 install to try and run Odin.

Thanks for any help you can provide!
--

S3 running Poland´s JB. Please someone, port Sammy´s camera and unlock notifications to CM10!