I have Sonar Platinum and was wondering if comes with anything like Logic Pro Impulse Response Utility, or other convolution engine/processor, I could use to create custom guitar cabinet impulse response (IR) WAV files.
 

No it doesn't. Voxengo has one for sale though.  

Thanks.  I did find the Voxengo deconvolver online.  
 
Fruty Loops FL Studio also has a convolver which can sample plug ins also.  
 
Kind of a shame that some of Sonar's competitors, Logic and FL Studio, have convolution utilities.

I haven't tried it with guitar cabinets, but I have upgraded to the full version of Rematrix and played around with putting an impulse thru some reverbs I like and then imported the wav recoded into Rematrix and that worked. You can search the web for impulse wav files. I'm on my laptop and don't have the files here. That should work with cabinets, but you'll need a transparent amp to drive the cabinet, otherwise you'll also get the sound of the amp as well.

You can also make some pretty cool reverb IRs with pink noise.