use ExtUtils::MakeMaker;

my @dbds = qw(DBD::mysql DBD::Pg); # whatever
my @installed = grep { eval "require $_" } @dbds;

my $answer = prompt ("I can use the following drivers: @dbds. 
You have the following drivers installed: @installed
Please type the drivers you want to test, seperated by a space:","@installed");

my @use = split / /,$anser;

open  F,"> dbds_for_testing.pl" or die $!;
print F "\@DRIVERS = qw($answer);";
close F;

WriteMakefile(
    # ....
    'PREREQ_PM'     => {
        map { $_ => 0 } @use
    }, # e.g., Module::Name => 1.i

    # ....
);