None. He's referring to Maelstrom Weapon... each time it procs you get a buff. When you get 5 stacks of the buff you get an instant cast. The buff stacks aren't combo points, but their function is very similar.
nUI displays the number of maelstroms in its aura (buffs) list, and possibly elsewhere. It tells you each time the number goes up (visual message), and give a visual message and audible warning when it's time to lightning bolt (or whatever). The mod has some other advantages - it tries (pretty successfully, imo) to put stuff in the right place, and to provide one addon to replace a bunch of others (action bar, raid frames, etc.) It's not the "points only" thing you're looking for, but it may, in the end, be a good solution.
Try this it, havent tried it personally but it supports Maelstrom and Serendipity (priests) charges. Im pretty sure newer versions of TotemTimers includes a bar display for maelstom charges, however I had to disable it as it didnt play nice with rActionButtonStyler. 10min of fiddling around with Power Auras should have easily covered your needs though : /
Edit; Whoops I guess Nug responded to your request very fast, oh well enjoy!