I assume that you are talking about a 62/63 part running in NORMAL mode. If so, just make sure the TOC is empty. Then flashboot will see TOC2 as invalid and assume that your vector table for the CM0+ starts at 0x1000_0000. It will check the first two vectors, the Stack Pointer and the Reset Vector. If they are both in valid areas of Flash and SRAM respectively, the device will execute at the reset vector location at 0x1000_0004 and ignore the TOC2.
Thank you! This is good information to have!