Grab Bero's Quake II at Games on Sbiffy under QuakeII.sbi
In Selfboot Inducer, make sure all three SBIs are selected with a + sign in the right hand column (if not, highlight it and click select)
Choose Single Menu under Select a Menu Type.
Click the icon that looks like a barcode to extract...
Grab selfboot inducer v4 from http://www.consolevision.com/members/sbiffy/
It's at files under Current.zip
Extract Current.zip and install Selfboot Inducer.
Grab the nxDoom 2.2 sbi at Games under NxDoom_2.2_bO.sbi
Grab Bero's DCQuake at Games under Quake.sbi
Put both sbi files in...