What is the best way for me to export some 3D text preset or comp from After effects cs5 to Premiere CS5 where I can apply it to a scene in Premiere?

The best way would be exporting it in lossless with alpha, which preserves your alpha channels and lets you drop in on any background you like. It it a big file though, and premiere might have trouble playing it back while your editing. If you need to time it with music or you need to do any type of adjustments in premiere, I would suggest exporting it at draft quality, so that you can play it back, and then export it in full HQ and just replace the footage after you're done with your work in ppro.

Cheers!

You could also use dynamic link, but I would only recommend that route if you have a powerful editing system.

thanks this helps