I don't really follow. The ISP sketch needs to be loaded onto an Uno and then that can be used as an ISP tool to upload firmware to the tiny85.
Do you have an Uno that can be programmed with the ISP sketch?
Also if you are going to program with ISP, then use
Mellis core GitHub - damellis/attiny: ATtiny microcontroller support for the Arduino IDE is for the Gemma
The Gemma is (or was) part of the default Arduino core, it has a bootloader that works over USB (when it works). So, in theory, you can load the Gemma bootloader on the tiny85 with the ISP tool and then unplug the ISP tool and program the tiny85 over a USB as a Gemma (if you can get that to work).