Toyota Repair: Front end problems, alignment problem, size tires

Question
Can the alignment of the truck be checked by just putting the vehicle on the machine?  I'm having tire wear problems.  Have a Toyota Tacoma 2WD 2003.  Started eating tires at 12000 miles.  I thought the front end was out of alignment and took it to mechanic to get lined up.  He told me shocks were no good and that alignment wasn't that far off.  He lined up and rotated tires.  Seemed OK for a while.  Started eating tires again so I bought shocks and replaced them myself.  Old shocks didn't feel all that worn out to me.  Kept right on eating the tires.  Took to dealer who told me the shocks weren't the problem and it was just a matter of rotating the tires every 5000 miles.  Said the cure is to replace the tires and line up the car.  I dopn't know what to think.  Can the truck just be put on a machine to check alignment out?  Is it stupid to line up truck without replacing the tires?  Is the dealer just blowing smoke here?

Answer
You should have taken it to the dealer in the first place because everything is still covered under the warranty and should not have cost you a dime,the reason the tires wear is that there is an alignment problem, did you hit anything or otherwise cause the alignment to go out, if so, the warranty is void,shocks don't go bad at this mileage, period.
Are they standard size tires and rims?
Yes you can have the truck put on any alignment machine to check to see if it is within specs.
I suggest you do that first before replacing any more tires.