Hi openmindedcomedy,
I assume you do have not have the binding pose in mind, which would align typically with a Symmetry plane as orientation. Anything else might be not simple to define while the character is in an elaborate pose (all parts are moved, for example)
You could try to create a clone of the IK to the other side and use it as a guide or even position snapping. Then delete the clone.
https://help.maxon.net/c4d/s24/en-us/Default.htm#html/TOOLCAMIRROR-ID_CA_MIRROR_TOOL_GROUP_OPTIONS.html?TocPath=Character Menu|Mirror|_____2
but you might notice that even this function, with so many options, will have difficulty keeping up with a posed character.
But perhaps, check out the CV-Too Forum and request a script. Maybe one of the Character/Script Gurus might have an idea.
Here is a little setup; see the file below. The Mirror plane needs to sit where the Symmetry plane needs to be. The Right null takes the original pos, and instantly the Left one places itself. These positions can be copied easily. (Or just position/Axis Snap.)
All the best