Shouldn't the author be able to update this program to fetch the v18?
*edit* see the line in the source for the shop. It's in installer.c
printf("\nAttempting to install Wii Shop v17\n");
ret = patchmii_install(0x10002, 0x48414241, 0, 0x10002, 0x48414241, 0, 0);
don't know how to alter it...