I think that crossing into Israel is simply impossible but that the border with Syria is technically open so it might be possible to find a shared taxi from Damascus or something. Of course, you need to get there in the first place and the whole of Syria and even large parts of Lebanon (the entire Bekaa valley and all land borders) are not particularly safe and completely off-limit as far as any official travel advisory is concerned.
Options to come by sea are limited as well. I am aware of some freighters taking passengers and stopping in Lebanon but that's not cheap and they explicitly disallow disembarking there. The only halfway realistic option therefore seems to be a ferry from Taşucu to Tripoli but it seems that it's not operating at the moment. Tripoli itself is not as bad as the border but still not particularly recommended. I haven't been there personally.