What program is best to cook a ROM

[Asphyx]

I second the Calkulin reccomendation!
There are lots of options in there and visual kitchen takes some getting used to...but if you start off by selecting the devive then select the sys you want to use, the rest of the process will be similar to buildos. Just turn on the packages you want and turn off the ones you do not.

Leave the sysy and oem files alone though. just select from the ext packages when configuring.