I have Sonar X3 Studio, i recorded a key riff on a track but i want to add some distortion.
i want to run a cakewalk audio track out of my computer into a stand alone tube screamer "distortion"
and back into cakewalk on a new audio track...
I looked all through the help files and couldn't find anything on the subject.

There is an External Insert plugin for that  I don't know if Studio has it or not but Producer does.

What you want to do is called 're-amping' 
 
All you need to do is route your signal to the output of your sound card form inside sonar and insert it into any effect you want,  then route it into the input of your sound card and back into sonar. No need for external insert if you are re-amping. External insert is for mixing in real time with outboard gear as it calculates the latency. 
 
CJ

CJaysMusic
What you want to do is called 're-amping' 
 
All you need to do is route your signal to the output of your sound card form inside sonar and insert it into any effect you want,  then route it into the input of your sound card and back into sonar. No need for external insert if you are re-amping. External insert is for mixing in real time with outboard gear as it calculates the latency. 
 
CJ

WOW that sounds too easy here i am looking for vids" and reading through all this stuff
thank you so much, i'll give it a shot..

You may have some problems matching impedance and volume though. The signal coming out of your soundcard will generally be too loud for a guitar stompbox, and likewise you need to go back into the computer through a high-Z input or DI.

I'll use DI, good point about the VOL" gonna run it a few times i'll start out low..

Thanks for the info" it worked great, Guitar's and Keys sounded awesome..

Have yourself some good mojo.

Glad to hear it!