State of the art for DOS L2 is that two lems are lost in the entire game, one is the blocker in Magnificent Severn, and one in Snowed In (Polar tribe).
So Close But So Far Away (gold is lose-4) uses vertical crawling for lose-0, whereas crawling doesn't exist in L1 and very likely not in the PSP version either. Tension Sheet, which you've already seen, uses the overlap of miner and basher, which is already hard to time in DOS L2, and I don't know the exact PSP physics either to tell whether it's possible there.
Secret of Nimh has a lose-0 method in DOS which I don't recall exactly, but cc was among those who discovered it. The fundamental idea is to eschew the blocker, and instead send lots of climbers over the wall to dig it away AT-style, generating a walkable slope when running out of climbers. DOS L2 has horrible selection priority, so execution was a hassle in DOS.
Keep in mind that all of the better-than-gold solutions in DOS L2 are probably oversights of the developers, and the intended routes do not allow anything better than the gold requirement.
-- Simon