If you can get your BB tool on the end of an impact wrench...there's little to beat it.
I had a stuck BB for over six months. Sawed at it, chiseled it, heated it, chilled it, vice etc. It was a mess and nothing was moving it. Stuck the bottom bracket tool on the end of an impact wrench and it was out in under a minute. Do at own risk etc - as I don't think BB tools are designed for it...
I have seen people weld steel bars to BB cups too so that might be an option...