you can find related information inside the Target Specification file under "CAN Bootstrap loader".
I am not quite sure about the tools, but if you look inside the documentation every single message is well described. Even the program flow is clearly explained in "CAN Bootstrap loader flow". The only thing you need is a CAN controller+transmitter. You could use for example an additional AURIX-evaluation board or -triboard to build that CAN bridge. That is up to you.
Could you please specify the name of the file? I've checked into the ones listed on myicp under Target specification but there is no reference for the bootstrap loader.