Another workaround is the record the effect to a scene. assign the scene to a fader with ipcb faders. fader should now control the size of the effect(remember to record the effect large as you can only control the size from stop to the recorded size). You can then press and hold the choose button for the fader and use the second encoder wheel while pressing the choose button to control the speed of the effect both slower and faster than recorded.
Another workaround is the record the effect to a scene. assign the scene to a fader with ipcb faders. fader should now control the size of the effect(remember to record the effect large as you can only control the size from stop to the recorded size). You can then press and hold the choose button for the fader and use the second encoder wheel while pressing the choose button to control the speed of the effect both slower and faster than recorded.