I haven't used it in several years, but I think it's still the same material. You use a wash coat of sealer, that is, sealer that is reduced by about 50% with the appropriate solvent.

One coat properly applied usually does it. The trick is wiping it on and allowing it to dry just enough. Too little dry time and the filler is pulled out of the pores when you wipe. Too long and it is a bear to wipe off. We used burlap for the first wipe followed by a soft cloth.

Here's a link to one supplier:

Here is a link that might be useful: grain filler

Grain filler only works on unfinished wood- it requires that the wood be able to draw out some of the solvent to flash dry it from underneath; it will not do to rely on it drying from above (air) for it won't stick, and when you wipe off the excess with burlap, it would all be excess!
You'd be better advised to try two or more coats of fast-drying oil-based sanding sealer over your previously-finished woodwork. That will fill the oak pores just as well as grain filler.
Don't use a lacquer-based sealer either. That will possibly foul up the original finish.
Casey

Well Thanks folks! I shall proceed as advised.

I don't usually post to this board but there are some procedural questions. First,remove the cabinet doors and hardware and thoroughly sand the doors and frames. Then, you can begin the priming process with a primer perhaps tinted with the final color. Even using an oil based primer, it will raise the grain some so you will need to resand after the first coat of primer is completly dry. Then apply the second coat of primer. This process should should give you the grain free surface you are looking for.

I would then use a good matte finish paint which can be either oil base or latex. If I was doing it I would have the doors professionally sprayed although you can obtain a good surface using a good quality brush.

there is a right way to approach this project if you want a quality job.

I agree with tex. Remove everything that you can and lay it all out and spray an easy sanding enamel undercoat on all surfaces. Let this dry and spray another. Then sand it down till surfaces are flat and grain is full of undercoat. Then you are ready for finish.