This is going to be a tad bit long. Feel free to ask any questions if anything isn’t immediately clear to you. I’ll be out at work for a bit but will be around in a few hours, and I’m sure someone else will come along that can give you good advice as well.
I don’t have an Analog 4 yet (getting one soon), but I have a little bit of experience with CV sequencing (I have a Moog LP and a Voyager Old School). I’m pretty sure you can still Parameter Lock steps on the CV track, although there’s a bit of a catch when it comes to opening up the possibilities of full control. I’ll explain.
One important thing to keep in mind is that the Slim Phatty (or any CV synth) has separate inputs for Gate and Pitch. The other real important thing is don’t send two CVs to the same destination.
Both need to be triggered in order for a proper sequence to play: a Gate CV will trigger the Envelopes and a Pitch CV will (obviously) determine what note is played. This differs from MIDI sequencing, where a “Note On” message will do both.
The Analog 4 has two CV Outs; out of the box, both of these will be used up just in order to do any basic melodic sequencing. If you just send a Gate CV, the Slim will only trigger whatever the last note played was. If you only send a Pitch CV, you’d have to trigger the sound by pressing a key, more or less defeating the purpose of sequencing.
Using it in the traditional Gate/Pitch manner would leave you without any free CV Outputs left to do things like affecting the filter. However, fear not, since there are some options, and they’re both fairly simple.
Option One:
Do you have any of Elektron’s other stuff? If so, you could simply use their MIDI tracks to handle the basic melodic sequencing, which would free up both of the Analog 4’s CV outs to do as you wish.The Octatrack would be the best match, since it’s sequencer is closest to the A4’s. Keep in mind, you don’t NEED anything else from Elektron; any MIDI capable device (or computer, iPad, etc) can be used.
Option Two:
If you don’t mind spending about $20 dollars (a lot less than buying an Octatrack!), you can get “insert cables” which can split one output to two sources. This will let you use one of the A4’s CV outs and send it to both Pitch and Gate. That can be set up in the A4’s menus: assign “CV A” to Gate, and “CV B” for Pitch.
That would take care of your basic CV duty, and leave you free to use the A4’s other CV Out. From here you could just use a normal patch cable if you only want to affect one thing, or you could repeat the ‘trick’ with another insert cable if you’d like to use “CV C/D” on both the Filter and the Volume.
Here’s a VERY helpful site I found detailing this method with the more technical aspects: http://analog.pen.io/
Hopefully this helps!