The easiest way to accompish this is to unlock the cells you want to TAB between and protect the worksheet.
To do this:
Select B2, mouse right-click, choose Format and go to the Protection tab. Uncheck the "Locked" box. Go to B4 and do the same.
Now, go to Tools|Protection|Protect Sheet... to protect the sheet. (you can put a password in if you want, but this isn't necessary)
You should now be able to TAB between B2 and B4. To add additional cells, unprotect the sheet and "Unlock" whatever cells you need.
HTH