returning dataset from clr functions

Hi
Im trying to get dataset (table etc) from clr function/procedure. I know
there is VTF functions that allow return table of values. But this requires
specify columns that function returns.
There is also SqlContext.Pipe.Send - so I can pass sqlReader and get table
of values retuned by reader.

But i want to connect to another database (pervasive), get dataset from that
database and return table. I want to pass any query to function so i cant
use VTF function as query may be vary every time. And i cant use Pipe.Send
because im getting data from another database (using pervasive objects
including reader - so i have no sqlDataReader to pass it to pipe.send).

any idea how to return just DataSet?