Hi Morgan.

Two cents in your box ;-)

In addition to hardware bits ( flags) that are implemented
in hardware to handle interrupts properly you can define
you own additional software flags. I mean the following:

1. Define ( reserve) set of flags such as soft_flag1 , soft_flag2 , etc..
2. Set required flag (soft_flag1 = 1 for instance)
3. Set GIE flag by software
4. Your ISR should test software flags and jump respectively ( ISR1)
5. Finally ISR1 will clear soft_flag1 and execute retfie cmd.

The only thing I can see is situation if you don't have to use
global interrupt flag (GIE) for some reason ( disable interrupts
at all for some time for instance). So this trick probably could
be implemented in different way.

Good luck in your research.

WBR Dmitry.

PS. I didn't test it in reality yet but it looks workable enough.