Would it be possible to use magical knack on say a straight unchained rogue to boost my caster level for my spell like abilities from minor and major magic by two since the caster level is my rogue level minus two?
No, as you have to choose a spellcasting class and the unchained rogue, even with those talents, is not a spellcasting class. This is why you can't choose Arcane Strike as a feat, either.
I would have preferred if the unchained versions of those talents gave actual spell slots that one could use to cast the spells, personally, and I might so houserule in a game I GMed.
In any case, you can always ask your GM, unless this is for PFS, and she might decide to houserule it for that purpose.
Unless it was FAQed the trait doesn't say anything about it needing to be a casting class. Also you can't take arcane strike because you can use SLAs, not spells, which doesn't seem to be a related issue from the wording of magical knack, it simpl states you gain a bonus to your caster level in that class, and in the rogue class you can have a caster level associated with your rogue level.
Actually, now that I'm looking at it, the Major Magic talent in the unchained rogue says you use your rogue level as your caster level, not minus two.
Huh, didn't notice that. Well then how about the Charm person spell like ability I get with the kitsune trickster archetype, it does say use your rogue level minus two. Any chance I could boost that with magical knack?