You'll need to experiment but there are two options.

1. Rename your Tour app AND set the attributes so that they are the same as a System 6 Finder.

2. Examine the boot blocks of an existing system disk using an editor such as Fedit or Norton Disk Editor. The name of the startup app is specified there. You'll need to use an editor that understands the format of the boot blocks, not just a binary/hex editor. Then copy the required parameters to the boot blocks on your Tour disk.