alter or setting keyframes

hi everyone,

does anyone know if it is possible to set keyframes or to change their values using an expression?

i kind of want to do the following:
either: - create keyframes at these times and give them these values
or: go to already existing keyframes and give them these values

when i set values triggered by a certain time there is no interpolation and the value remains 0, except for the exact trigger time. also when i set keyframes manually (which would be fine) and tried to change their values, it took no affect, unless on the exact triggertime.
when i use the linear interpolation expression it only seems to execute the last expression.
either way, when i do convert expression to keyframes it sets a keyframe on every single frame. but i need to have the keyframes at the right positions, to play around with the interpolation later on.


help would be very very welcome!

thank you
kay