I don't think the Mind Eye Society would allow such house rule.
If you were playing a regular game, technically, you could pick the merits the Storyteller allows you. So, if you come up with an explanation of why your character have those traits, he could allow them. In this concrete case it's difficult because they are based on the Masquerade Gangrel weaknesses. But still, if your Storyteller find it cool, or at least reasonable, he could grant you those mutation abilities, or even change your weakness.
Or you could belong to a bloodline with that weakness or power.
As a response, to the more general question of the title, there is a guide to use Masquerade material in Requiem and viceversa. This material is optional, and I don't think any LARP club is actually using it, but traditional roleplaying groups could if it pleased them. Let's see what it says about gangrels:
Of the three clans that appear in both Masquerade and Requiem as full
clans, the Gangrel are probably the one that changed the least. Both
versions of the Gangrel are animalistic and self-reliant. Masquer- ade
Gangrel focus a bit more on the wilderness and dwelling between
cities, while their Requiem coun- terparts are simply predatory,
rather than strictly animalistic. Requiem Gangrel are also a bit more
willing to join sects and spend time around other Kindred, but beyond
that, a Gangrel character can be shifted between the two games fairly
Requiem Gangrel: The Gangrel are already a core clan of Vampire: The
Systems: The system that needs to switch over from Masquerade’s
portrayal of Clan Gangrel is the weakness. Every time a Gangrel
succumbs to frenzy, she gains an animalistic feature, such as slitted
eyes, tufted ears, wolf-like hair, and so on. While the system
presented in Masquerade for these features (for every five, the
character loses a dot of a Social Attribute) can be ported to Requiem,
it seems a bit harsh. An alternative might be that every three such
features imposes a –1 penalty to Manipulation or Presence rolls,
except those made to Intimidate.
The favored Attributes of the Gangrel remain Composure and Stamina.