Get WHERE string apart from other SQL

[Crusader4Christ]

I need to make many manual db-requests, something like
SELECT count(d.id) FROM download d JOIN download_history h USING(download_id) WHERE ...
and other more complex queries
So main part of query can`t be generated by waterline, BUT I want to use waterline where clause builder. How can this be done?
It will be good if waterline can return query text or it parts.

[OPADA-Eng]

I need the same thing, Any suggestions ?