Conversion of barbituric acid to veronal This is just out of curiosity. I have no intention or authority to do conversions.

I am studying chemistry of tranquilizers, in that an important class is of barbiturates, which are also hypnotics. The structure of Barbituric acid and veronal, are similar, except veronal has two ethyl groups instead of hydrogen at lone $sp^3$ hybridised carbon. How can I convert Barbituric acid to veronal? 

I thought that making carbocation or carbanion will help, but I don't think carbon will get negative or positive charge until nitrogen has hydrogen. Probably we'll have to protect nitrogens, am I thinking right?
This paper from Tetrahedron Letters here details synthetic procedures using carbonyl compounds in solution with barbituric acid and Pt or Pd hydrogenation catalysyts to give reductive di-C alklyation. This includes examples of N-unsubstituted barbituric acids R1 = R2 = H. Using barbituric acid plus acetaldehyde should give you veronal in a single step.