| Do a search on Talkbass for something like "tabs timing" or "tabs rhythm" - the subject has been discussed several times before, including recently.
It boils down to the fact that you can devise some form of supplementary notation to denote the rhythm. However, especially if sharing via the Internet is not a major consideration, you may find it more useful to use standard notation, which tends to be easier to read at sight and helps you see how the music is fitting together rather than keeping you just 'playing by numbers'.
Wulf | 
Tabbing your own music... 
