Well, I was one of these people a while back. All you need is time, something to write with, and something to write on (lines are important).
01. I started off by drawing the Bass neck and listing all the notes up to the octave (12th fret).
02. Next I drew a table that showed each note from fret 3,5,7, and 9 on each string.
03. Now comes the fun part. You will need to start on the G string and write down A#,C,D,E over and over down the paper, then do another row. Fill up the paper front and back doing this. Say it to yourself as you write it, and try not to look back at what you have already written.
04. Do the same for the other 3 strings:
05. After you do this enouph, it will stick into your head. Then try going down the neck of your bass to get a hands on feeling of it. Try going down the bass on one string, and go backwards saying the name of the notes on each of the frets. Try the next string after that, ect. Remember, it all stars over on the 15th fret, so all you realy have to do is 2,5,7,9 because the 12th is ovbiously the same as the sting you are playing.
06. Now you just need to know what the whole and half steps are, and you can easily figure out which note is which if you know the frets.
07. Also, if you know 1 string, you know 2 strings. Pick a fret on string G. For example, Ill say D on the 7th fret. Go up 2 strings, over 2 frets and its the same note (A string, 5th fret).
There it is, the easy way of knowing the neck in a few days. Hope I helped.