IK/FK Stretching

Hey..

Been working on an arm setup with IK/FK stretching. The IK stretching is achieved with a float script;

if (dist-straight)>0 then
(
(dist-straight)/2
)else
(
0
)

Where dist is the distance between the shoulder and the hand, calculated with exposeTM. The straight value is the distance when the arm is straight.

Then the FK stretching is achieved by wiring a spinner to move the FK control objects.

I then want to be able to snap from IK to FK while respecting the FK stretching. Anybody got a good solution??