As far as I know, there are no canon rules for using standard hermetic spells to increase longevity. Magi have longevity rituals, but could you use normal magic instead?
Covenants has a Health attribute for laboratories which gives a bonus to recovery rolls, and half a bonus (rounded down) to aging rolls. Normal magic has a guideline for recovery rolls, what if we created a guideline by extrapolating from covenants?
Base 15 grant +18 to wound recovery rolls
could be turned into
Base 15 grant +9 to aging rolls.
This would allow a magus to craft spells to aid in longevity - it could allow for a lot more experimentation.
A longevity ritual to give a +9 bonus would be a CrCo Lab total of 45.
A longevity spell to give a +9 bonus would be (base 15, +2 sun) = lvl 25. To invent this would need a CrCo lab total of 50 - but no vis!
So could magi have spells cast on them to provide a bonus instead of using a longevity ritual?
The Longevity Ritual IS the CrCo enchantment to increase longevity.
Even accepting that you could derive/discover a guideline that granted a bonus to Longevity Rituals and cast it twice daily (what happens when you forget to cast it?) you would still be under a mystical effect, and would therefore accumulate 1 point of warping per year, anyway.
But this is a bad idea, for multiple reasons, the first of which is what happens when the magus isn't able to cast the spell on himself for a day.
The eventual aim is to enchant it into his familiar bond so he has a longevity ritual with no warping.
....and that was pretty much why my troupe veto'ed it unanimously.
IMO, no, just no.
It's kind of a big deal that Bjornaer wouldn't be able to take advantage of such a breakthrough. In addition, it should be a breakthrough, a Hermetic one, in which case you've already taken significant warping from your regular longevity ritual AND your research and stabilization efforts. So, kind of moot, but if great benefit for later generations, the Order thanks you for your contribution...
The answer is "this is not how Hermetic magic does this particular effect."
Vitkir and Learned Magicians, for example, do have longevity effects as regular spells, but the Hermetic longevity ritual is not a spell but a laboratory procedure.
I'd allow making it a spell as a Hermetic Breakthrough. Followed by another either Major or Hermetic Breakthrough, to either turn that particular spell guideline into non-Ritual (Major), or make it possible for Familiar bonds to carry Ritual enchantments (Hermetic).
Basically, feel free to start the process, but you won't have any use for it by the time it's completed, because you'll either be long-dead, or you'll have used some method of gaining Might to achieve immortality. In either case, you have to weigh your options about if you think it's worth it.