Start off as if you were going to be constructing a preset, but just never SAVE it.
So, for example, MENU -> P4. Then you're presented with the 4-item primary menu, with the first two items providing a way to select the PRIR and HPEQ you wish to "load" (i.e. "bring in").
Push OK (after up/down-arrow navigating if necessary) on PRIR or HPEQ. Then use left/right-arrow navigation to INTERNAL (to browse the contents of internal memory cells for PRIR or HPEQ) and push OK.
Then use up/down-arrow navigation to scroll through your internal memory contents until you find the PRIR or HPEQ you want to use. Then push OK, and it will display "LOADING FILE". When it completes, you'll be back at the primary menu list to choose PRIR or HPEQ (or to save it in the currently selected preset, or to erase the currently selected preset).
Now push EXIT, and you're at the Realiser main display. The PRIR you've just selected will have been "brought in" to be active. You don't have to save it if you don't want to.