How to get from Vienna central station to Vienna West bahnhof?

It's probably a bit too late but I'm gonna answer anyway..
The interesting part would be how you definate "central"
If you mean Stephansplatz => just take the U3 in the direction Ottakring
If you mean cental station as in Hauptbahnhof => U1 in the direction Leopoldau, leave the U1 at Stephansplatz, then follow the directions I listed before :)

I hope you had a good time in Vienna :)