Specific genderbend with alien!biology search and a more general genderbending one

[bigmamag.livejournal.com]

I read this fic earlier in the week and forgot to save it.  Spock has to disguise himself as an alien woman to secretly get Jim out of a dangerous situation at this fancy party, and to disguise himself he turns himself orange like the natives, exfoliates all hair, and gets a wig from Uhura. Then he locates Kirk in a bathroom, servicing a woman, and manages to make Jim want to go with Spock more.  Things turn heated and Spock gives into having sex with Jim (whom he is secretly in love with,) and I remember that Spock's biology consisted of a retractable penis and had it where he had a canal like a woman but not.  Then after Spock sends himself to the brig for "assaulting" the captain.  

Yay specifics!

And for a more general search:  I'd LOVE any and all genderbending recs, but please GOD no always-a-girl ones or ones where they change all the pronouns (ex., "Kirk went to her quarters..." NO.)  If you can provide me with some of these in TOS form, I may have to make out with you a little.  Delicious tag links welcome.  :)