The only way would Seifer acknowledge as a way to get him properly awake was sex. Of course.
Which clashed somewhat with Squall's morning demand ('Coffee. Now.'), but surprisingly, they got around it quite well (with no duels in the training center, or even the contested flip of a coin; it just became the unspoken rule between them). Whoever woke first got to wake the other, and it had damn well better be the preferred method or it would be a day of extreme grumpiness (and if Seifer deprived Squall of coffee, no doubt he wouldn't be getting any, so he was best advised to get the damn coffee).
Some mornings, Seifer would wake up first. Then, since he was awake, he'd get out of bed (cursing loudly in hopes that Squall would wake up anyway, but he never did, just to be stubborn) and find coffee for Squall. Strong, black coffee with as little added as could be (how Squall liked it best; Seifer claimed it wasn't spoiling him, because it woke him quicker). And then, never mind that he was already awake, he'd demand that Squall wake him up properly (and by that point in the day, Squall was usually quite eager to do so).
If Squall woke up first, he'd close his eyes again and deny it for a long time, sometimes even until Seifer started stirring anyway. But either way, if Squall woke first, Seifer got exactly what he wanted to wake him up on a morning. Either Squall would wake him up with kisses and gentle (always a little hesitant) touches, or he would wake up, lean over, and steal his kiss and that'd lead the same way anyway.
Other people in Garden just didn't know how they did it (not the sex; the living together - they could imagine the sex happening, rather vividly, and some probably dreamed of actually seeing it - but that's another story). Some mornings they could swear the two would rather go back to their old tendencies (and try to kill each other) but they always seemed to work it out somehow (which disappointed those who would have liked to witness those famous duels more often).