I’m wondering whether what you might really be asking is “can I slave my friend’s Ableton set-up to my Cubase set-up using MIDI time code”?
If so, then yes…
In this situation you’d just need to connect MIDI out on your system to his MIDI in- probably with a standard 5-pin DIN to 5-pin DIN MIDI lead.
This way, you should be able to keep the two systems in sync - the proviso being that you’d have separate ‘arrangements’ running on each machine, but with the advantage that you need not be running the same sequencer/DAW on both machines. The software running on the ‘slave’ machine though must have the capability to sync to external MIDI time code (which most do). …and you will probably need a mixer, or sufficient low-latency I/O channels on each machine for real-time inter-connect.
But if you really do need VST System Link, that’s a whole different ball game, and requires much closer integration of the two systems - including available digital audio I/O channels on all machines. VST system link is about using CPU resources on the slave machine(s) to supplement the master. You would need two (or more) copies of Cubase or Nuendo though… To make this work, you’d need to have a good understanding of digital audio clocking, and probably you’d want an external mixer, or some available spare digital audio I/O on your computers. It’s not for the faint-hearted or noobies. (no insult intended:-)
Are you sure you really need this? MacBook Pro is well specified modern machine…if you aren’t intending running multiple orchestral sample libraries and CPU-intensive real-time FX, I doubt that you really want the complexity and compromise that goes with VST system link. After all, bouncing heavy duty VST tracks to audio, or freezing, are free, quick, easy and 100% in the box with Cubase and Nuendo.
I’m working here on a single 6 year old dual-core 2.6ghz PC with just 4Gb RAM. I’ve produced more than 50 commerically-released tracks on it this year - almost every one of them with typically 40-80 mixed audio/MIDI/instrument tracks and multiple VST FX per audio channel. The PC sits at less than 50% CPU most of the time. RAM never gets maxed-out, and the latency/audio-glitching compromises rarely give me problems.
It’s my guess that VST link, in it’s current guise, hasn’t got much life left in it now. PCs are so much more powerful, and multi-channel networking solutions based on Ethernet/MADI et al are more likely to be the next way forward.
If you don’t already have serious identified performance problems, I recommend you spend your time making music…