How to Use expanded I/O to communicate with some bus devices (TM1637 for ex.)

Hello.

On my little arduino board I have already used all my I/Os for several bus connections.
But I have a lot I/Os more through some port expanders (PCF8574P).

I want to add a TM1637 based 7 segments display and would know if it's possible to use it through the I/Os from the port expander.

My I/Os on my PCF8574P work great but I don't know how to use it as with the arduino pins with the TM1637 librarie. Is it possible?

Thank you for reading (sorry for my english...)

http://wiki.seeed.cc/Grove-4-Digit_Display/
Looks like some kind of serial interface using 1 signal wire.
Any way to swap with another pin and make life easier on yourself?

CrossRoads:
Grove - 4-Digit Display - Seeed Wiki
Looks like some kind of serial interface using 1 signal wire.
Any way to swap with another pin and make life easier on yourself?

Thank you for the answer but my question was how to use bus devices on extended I/Os.
Do you know if there is a way to use the extended I/O as classic I/Os?
I don't find how to use the TM1637 libraries (or any bus device) with extended I/Os.