how are you currently jailbreaking your PS3 ?
Typically, if you have a programmable Jailbreak device, there are steps to install the .hex files onto that device. To put it in very simple terms, the .HEX files are known as payloads, as stated by costocart in the previous post.
As for me, for example, I'm using a Teensy V2.0 dev board. I connect the Teensy board using its USB port, and the provided software that allows me to download the .HEX file into it.
Hope this further clarified your question about how to change the payload. In regards to changing your BM, look for another post where I happen to ask a similar question, there are great replies to that which should give you the direction to go about changing (or using multiple) managers.