can you do an sas on an xterra with wagoneer leaf springs?

Yes, search is your friend
http://www.xterraownersclub.com/ubb/ultimatebb.php?ubb=get_topic;f=9;t=000295.

A bit soft but they will work on the front. With some weight, winch, and whatnot I would stiffen them up if I were going to see them for more than a trail rig.

Yeah, they're definitely a little soft.

ok thanks. what would yall think about using xterra rear springs on the front?

uh...why would you wanna use the extremely soft OEM flattened out spring pack to put under the front which (correct me if wrong) has a higher sprung weight (than the rear) especially with a built Dana 44, bumper, winch, etc; up there...?

Me thinks you got some reading to do before you start tearing off the IFS parts. There is a ton of guys on here that will help if you get stuck. Also, check on nissan4wheelers.com.

Good luck, happy wheeling!