use warnings;
use strict;

my @aliases = qx(ksh -c alias);

print "@aliases\n";
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However, this with create a non-login shell. What happens now depends on the versions of ksh you are using, and where your aliases are defined. Let me assume your aliases are in .kshrc. If so, then on ksh88 then ~/.kshrc (or the file defined in the ENV environment variable) will be executed and you should be fine. However on ksh93 it will not execute $ENV, so you need:

my @aliases = qx(ksh -c '. ~/.kshrc;alias');
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or 'source' whatever file your aliases are defined in.