I'd checkout the 4ms pingable envelope generator. It does attack and decay as this envelope does and has the attenuation control within the module via scale knob, equivalent to the pitch env initial. Curve at 12 o'clock and skew all the way CW you have the above linear envelope. Also the ping input can take the output of your clock so you can get for instance a pitch envelope of 500ms at 1/4 division if clock is at 120 bpm, which can be nice and musical and would function as the time control. Then all you do is patch the env out into the v/oct input of whatever oscillator u r using.
http://www.4mspedals.com/peg-kit.php
You can do this already if you have an envelope/function generator, oscillator and offset module, most oscillators have at least two cv inputs for frequency for this reason.
cheers!