erc-track-position-in-mode-line

erc-track-position-in-mode-line is a variable defined in `erc-track.el'.
Its value is

before-modes

Documentation:
Where to show modified channel information in the mode-line.

Setting this variable only has effects in GNU Emacs versions above 21.3.

Choices are:
'before-modes - add to the beginning of `mode-line-modes',
'after-modes - add to the end of `mode-line-modes',
t - add to the end of `global-mode-string',
nil - don't add to mode line.

You can customize this variable.