A few things I learned about the DT_INT routines is:

1 - You must have a copy of the DT_INT and ReEnterPBP code in the file where you save your current program. PBP3 will not search the computer and create a path. Thus, I have multiple copies of the code on my computer.

2 - It is helpful to open the DT_INT in PBP3 and look at how the "RX1_INT" is structured in the code, and where it is looking for PIE, PIR, etc. The K22 family is relatively new, and as you stated, OSCCON SFR is structured differently than for older chips. You may have to alter the DT_INT itself, or alter the way you INT_LIST your IntSource.

3 - At the top of the DT_INT (I believe for the PIC12F/16F) there are multiple wsave options that you have to comment out or uncomment, depending. I don't remember the -18 requiring that, but I may be wrong. On the lower chips, you must include one of the wsave options in your variable declarations of your main code (wsave VAR BYTE $20 SYSTEM for example).

I'd wager a guess the issue you're having is #1, your interrupt routines are not in the folder you're saving your current program.