Trying to understand your question: In the first post you were told how to find the right hand side of DEPLOY_PARAMS=$DOMAIN{HOST},$DOMAIN{IP},$DOMAIN{CONFIG} and now you want to extract what's within the braces? Like this:
use strict;
use warnings;
my $str='$DOMAIN{HOST},$DOMAIN{IP},$DOMAIN{CONFIG}';
my @result = $str =~ /{(.+?)}/g;
print "@result\n";
Update: Putting it all together:
use strict;
use warnings;
use Data::Dumper;
my %h = map {my($k, $v)=/^(.*?)=(.*)/; $v=[ $v=~/{(.+?)}/g ] if $v=~/}
+/; $k=>$v } <DATA>;
print Dumper \%h;
__DATA__
DEPLOY_TIME=300
DEPLOY_TYPE=OS
DEPLOY_PARAMS=$DOMAIN{HOST},$DOMAIN{IP},$DOMAIN{CONFIG}
DEPLOY_DEFAULT_STARTUP=$DOMAIN{STARTUP.INI}
DEPLOY_DEBUG=Y
DEFAULT_EXPIRY=900