Or you could use also vi, it comes preinstalled with n900. The controls are little bit odd though if you're never used it before.

Basically there's 2 modes in vi, edit & command mode, it starts with command mode, to enter insert mode where you can edit the text press i once, find the part you want to edit and change the values. To return to command mode hit esc. To quit write :x to quit & save or :q to quit without saving, or if it complains about changes not saved write :quit!