Hi,
I'm not suggesting that I've got a solution but several questions pops up while reading your post....
What frequencies are we talking about, to what kind of resolution do you need to measure and how often does it have to update the measurement for each input?

If the frequencies are low(ish) and you can live with fairly low update rate you might be able to use pulsin or count and measure one input at the time. Although I've never personally used the CCP module in capture mode to measure frequency I see no reason for it not work on multiple channels - even though the signals aren't in sync. However, a chip with many CCP modules will usually be big so you may be pissing away alot of space and features by picking that instead of the smallest device with one (or more CCP modules).

But again, what kind of frequemcy, resolution and update rate are we talking about?

/Henrik.