Not OpenSDA, but - since it seems that the P&E firmware for the FRDM-KL25Z considers even a KL26 too alien to flash, and I'll need a "lean" embeddable version anyway - I'm writing a library that can put the KL26 (and almost certainly also KL24 and KL25, probably also some of the more distant relatives) into debug mode via SWD, access the AHB (e.g., to toggle IOs), and that can also program the chip's Flash. The latter process is not very reliable yet since there still seems to be some protocol or timing bug in my implementation, so it often takes more than one try to get the chip flashed.
The code, licensed under GPLv2+, is in https://gitorious.org/anelok/anelok/source/libswd/libswd.c and you need to write the equivalent of https://gitorious.org/anelok/anelok/source/libswd/ben.c for driving your hardware. ben.c is more complex than needed just for the Kinetis since it also supports the TI CC2543 (a completely different kind of SoC) and has some code for debugging my hardware as well. But it should be useful as an example of how libswd expects to be used.
Regarding flashing, some of the other Kinetis chips seem to have different memory structures. Some hints for handling these can be found in OpenOCD, file src/flash/nor/kinetis.c
You could also try to write a hardware driver for OpenOCD and use their SWD implementation (which does things a bit differently).
My libswd is still pretty rough but if you're looking for something easily adaptable, then you may find it useful.
- Werner