This is untested, but

while(@ARGV){
   my $argin = shift;
   while ($argin =~ /^-/) {
     $argtype=$argin;
     $argin=shift;
   }
   if ($argtype =~ /^-t/) {$TARGET.=" $argin"}
   if ($argtype =~ /^-r/) {$RELEASE.=" $argin"}
   if ($argtype =~ /^-b/) {$BUILDTYPE.= " $argin"}
}
[download]

ought to do the trick. I've anchored the patterns so that 'touch-typing' doesn't end up as being a -t type argument.

--
Tommy
Too stupid to live.
Too stubborn to die.