You need a motherboard with BIOS that supports Drive B. This option hasn't been popular since the Pentium 1 days.
Now, here's an amazing thing: I've used BIOS editors and found floppy B support to be present, but hidden, in most BIOS versions. Because it's hidden, you can't set a drive type, and it's set to "none" by default. It's completely possible to use a BIOS editor to write a custom BIOS where Floppy B settings are shown!
But you have a Dell, which has the BIOS file incorporated into a DOS executable. So you would first have to figure out how to extract the BIOS from that file, then modify the BIOS, then flash the board.
<font color=blue>Only a place as big as the internet could be home to a hero as big as Crashman!</font color=blue>
<font color=red>Only a place as big as the internet could be home to an ego as large as Crashman's!</font color=red>