As I couldn't find any useful answers to this and needed to do the same thing.
You wire D0-D7 on the Adafruit board to one port on a VIA, you wire RD, WR, C/D and CS to the other port. RST goes to Vcc (it's got an onboard reset controller and software reset command). Vcc and GND go where you expect.
The current version at least has level shifters so it can all be at 5v.
Init the VIA to be outputs. If you are debugging this initially consider putting a set of 100ohm resistors on the data lines in case you screw up.
Commands are sent with the following sequence (idle state is CS high, RD high WR high, C/D don't care)
lower cs
lower c/d
put a byte on the d0-d7 lines
lower wr
raise wr
raise c/d
for each data byte
put a byte on the d0-d7 lines
lower wr
raise wr
then when the command is done raise cs
For read it's much the same except having sent the command byte it's
raise c/d
switch the data port direction to read
then for each byte
lower rd
read the data
raise rd
at the end switch the direction back after rd is high, raise cs
A good test is to read a few bytes from command D3. That should give you a sequence including 93 41 for the controller ID.
If you are using some of the clone boards be VERY careful about the backlight line, preferably don't use it as some of them are mis-designed and sink large currents through it if you pull it low.
Initialization sequences for Adafruit ones can be copied from the Adafruit libraries - it's just a stream of magic command incantations and delays. For the non Adafruit ones you can grab them from Dave Prentice's MCUFriend_kbv library and those seem to work with every cheap ebay ILI9341 board.
And that's about it. To draw you use command 2A and 2B to set an X and Y range, then 2C and keep firing pixels at it (RGB565 so two writes a pixel). If you need to take a breather you can send 3C to continue writing.
Don't expect to win any awards for performance, but it's better than SPI bitbanging. No delays are needed - the VIA is way slower than the controller.
In theory you can direct connect it to a 6800 or 8080 style 8bit bus (with shifters) but at the moment I've not managed to get that to work. The theory is you wire it to D0-D7, A0 (for the C/D line), and RD/WR/CS or their equivalent if the chip is in 6800 mode plus a chip select decode.
The non display parts are more mixed.
The SD you need to bitbang with the VIA. You need 4 pins for that which you happen to have left. The resistive touch screen needs A->D convertors so isn't really usable. The capacitative one would need bit bang i2c but I dont have one to try.
The clone ones generally multiplex the resistive touch screen with some of the other pins and seem to do so fairly randomly by board maker.
