I need help for this rewrite?

sub1.sub2.sub3.sub4...domain.com/dir/file

[akameng]

Hello,
I don't know how can create sub4.sub4.sub3....example.com
my document root is /home/t/username/html/ subdomain works fine, www.sub1.example.com/dir internally redirect to /home/t/username/sub1/html/dir
and then allowed only 3 series subs like sub3.sub2.sub1.example.com also to /home/t/username/sub1/sub2/sub3/html/

How I can add more than 3 series subs like
sub4.sub4.sub3....example.com?

I am in shared hosting plan, server httpd.conf used below code for above operation:

# rewrite the hostname ([www.]sub3.sub2.sub1.domain.com --> t/username/sub1/sub2/sub3)
RewriteEngine On
RewriteMap lc int:tolower
RewriteCond ${lc:%{SERVER_NAME}} ^(www\.)?(.*)$
RewriteRule ^(.+)$ %2/$1 [C]
RewriteRule ^([a-z0-9_-]+)\.([^/]+)/(.*)$ $2/$1/$3 [C]
RewriteRule ^([a-z0-9_-]+)\.([^/]+)/(.*)$ $2/$1/$3 [C]
RewriteRule ^([a-z0-9_-]+)\.([^/]+)/(.*)$ $2/$1/$3 [C]
RewriteRule ^([a-z0-9_-]+)\.([^/]+)/(.*)$ $2/$1/$3

# everything else goes under ~/html
RewriteRule ^(.*)//(.*)$ /home/$1/html/$2 [L]

any idea about this?