All 21 skills start at level 5 + racial bonuses
No class - no specialization or major skill bonuses, or faster rates
Skill rate is made faster to average out not having major/spec skills. E.g 0.8 actions/exp needed per level for all skills
For every X skill increases the governing attrbiute is raised 1
Novice/Apprentice/Journeyman/Expert skill increases give different X skill amounts to their governing attrbute - the higher the rank the more.
You level up once you have got +Y attrbiute points
nGCD + GotNoClass + setting the minor skill advancement rate to 1.0 (easy with Progress) achieves the first four things. Well, nGCD uses a far more complex skill-attribute connection than just one governing attribute, but it's basically the same overall.
The last two are technically possible -- easy, even -- but not a good idea in Oblivion. There's the issue I described above, where the inherent cap to attributes means that if you want them to increase faster with higher skills, they have to be very slow at early levels which is frustrating in multiple ways. But most importantly,
gaining levels in Oblivion is not beneficial. All a higher level really does is make the game generate tougher enemies. With any of the mods that take over attribute advancement, even hit points aren't really level dependent; they're based on skills, or on attributes which in turn are based on skills. If the system were changed so that raising higher skills gave quicker advancement, the optimal strategy would be to keep all your skills as even as possible so you can
minimize your level relative to your character's actual power. The standard optimization strategy in vanilla Oblivion is "minors as majors" -- choose the least-used skills for your class, so you can easily manage levels and attributes. Any class-weighted system, or any system that gives higher benefit for higher ranks, will yield a similar strategy.
Where Skyrim fixes this is by giving perks at each level, so gaining levels has a real benefit. Oblivion doesn't have those perks, and without them the Skyrim system is utterly broken. Now, this could probably be done -- but nobody's done it yet. The fact that there are several hard-coded perks built into the skill mastery system doesn't help, because you have to work around those to avoid redundancy or imbalanced stacking.