[3.5] Mussings on Assassin's and Rangers. Help needed

[Dusk Eclipse]

A few questions that arose for me thinking on making a ranger-ish assassin. Obviously the first idea was to make a simple Ranger 5/Assassin 10/Something 5 easy, simple and boring.

Then I started to think on ways to get the assassin spells on the ranger list, but I don't know of any official (as in first party source material) way of doing it.that lead me to think on the Sword of the Arcane order feat. I thought it could be interesting (and not overpowered) to homebrew a feat similar to SotAO but that instead of letting prepare Wiz spells, worked with assassin spells (which are much weaker IMO).
The problem is that I don't know how to adjudicate the spells issue, SotAO mentions preparing the wiz spells from the spellbook; but Assassin is a spontaneous class and I am not sure how I should factor that into my hypothetical Sword of the Shadow order feat.

I also thought on an ACF for the ranger styles, that got poison use, death attack and somethign else, but it was just an afterthought.

So thoughts, comments or ideas?

[WinWin]

Black Flame Zealot could work for ranger, though would require a rogue or similar multiclass for the required SA.

The Divine Magician ACF might be a good starting point if you are developing a way to gain Assassin spells on the Ranger list.

Picking something for the ranger to lose would be the tough part.

An alternative would be finding a way to access the Spell Domain. Anyspell could allow you to prepare any Assassin spell.

Scribing Assassin spells into a spellbook is technically possible, though they would not be usable by a wizard. Otherwise your character would require a scroll of the spell you wanted to cast.