So the library (see bitbucket) does now support all three kinds of mounting the display. Just use different argument at the .begin function like:

 myTiny7.begin(3);
//if your display is mounted normal use no argument or 0 else:
// 0: normal 		(default)
// 1: mirror 		mounted on the other side of the PCB over the IC
// 2: rotated		mounted on normal side (over the QR-Code) but upside down
// 3: mirror + rotated 	mounted on other side upside down 

Also Attiny85/456 based boards like the Trinket should be supported now. Then the default pin out is:
1: SDO serial data out
2: Clock
3: latch
Change this as additional parameter in the .begin function, if needed, like this:

myTiny7.begin(3, SDO_PIN, CLK_PIN, LATCH_PIN);