Go to a reputable FBO. If in SoCal I suggest Orion Aviation at KCRQ or whatever other reputable FBO of your choice in your area.

Tell someone exactly what you want to do ie. "I am looking to finish my instrument rating in XX days" Sit down with an instructor or maybe even a few and find out who is willing to work exactly with your schedule and if you put in the book work (alot of book work) on your time and come in ready to fly you can finish your IR without paying these high "accelerated training cost" that most places offer. Accelerated training is a function of your ability to put the time and effort into learning and that can be done anywhere. As a matter of fact they may even cut you a deal since you will fly XX hours in XX days.

I work from 5:30 am until 5:00 PM and i go to the airport after work for a two hour flight a few days a week and I managed to finish my IR in a hair over a month at 35 hours in a Beech Duchess. If you take the same formula and fly twice a day 5 days a week and you will be done in under three weeks