I would like to upgrade to 4.2.1 without upgrading my baseband

[Freebeer187]

Hi,

I have a 3GS (old bootrom) and I would like to upgrade from 4.0.1 to 4.2.1. I have all SHSH's on file. I would like to keep my baseband and not upgrade to Musclenerd's new baseband.

Is it possible to do this using a pc? If so, how? Will the jailbreak be tethered or untethered?

Thank you for your help!

[Simon]

You would need a mac to make a custom 4.2.1 without the baseband update