PostgreSQL full text search words delimiter
The "natural" way to do this would be to change or write your own text search parser.  While it is possible to do that, it is unreasonably difficult.

Do you want both '11.22.33.44' and '33' to show up as individual tokes, or just '33'?  If the latter, then maybe just preprocess your data by replacing all '.' with ' ':

replace(doc,'.',' ')


Of course you should do the same replacement on the queries as well before passing them to plainto_tsquery.