The CL2 rated wire police arent going to come arrest you for using something other than so called "inwall" rated wire. I have yet to see anything not pass inspection that was Low voltage. Do you have any idea how many people run that cheap crap speaker wire in their walls that has the one copper and one tinned or aluminum wire?
Now days its like everybody needs protection from themselves. And boy do they get it. Getting an inwall rated wire is not as big of a deal as seems to be what everyone thinks around here. The biggest advantage to it is the extra jacket because it gives you much more protection when pulling the wire. Beyond that it doesnt really matter.
The whole issue of 'in-wall' rated wire gets a little sticky. The NEC and other codes, like Building codes, are really all driven by the insurance industry.
So, if by chance something happens, i.e. a fire etc. the insurance companies will look for code violations, as a means to reduce their liability (as far as paying a claim) All this is to get the insured (us) to take on a percentage of the 'blame' for the fire or it's subsequent damage.
So, with that being said, I won't, in good conscience give advice that's against the NEC or could possibly harm others.
For example if the OP lived in an apartment or condo, his cheap non rated wire could harm other innocent tenants, with it's tendency to produce toxic fumes when exposed to fire.
The outer jacket on CL rated wire is for much more than just easy pulling.