Is it true that you can't compress the calipers on anti-lock brakes? Is there a way I could try to do it that wouldn't destroy the calipers?

I have never heard this, nor do I see any reason that that could be a possibility on any vehicle. At least, not as far as ABS alone is concerned.

Now, if the issue you are referring to is vehicles with 4 wheel ABS and/or rear disc brakes, then there is a grain of truth in the statement.

Almost all rear calipers require a special tool, and a special method to compress the cylinders. Simply attempting to compress them with, say, a C-clamp, will be unsucessful, and will damage the caliper since the pistons in these calipers often actually "screw" in.

The tool required, aptly named a rear caliper tool, or something similar depending on where you are, should be readily available at most parts stores.

The reason you're not supposed to compress caliper pistons on vehicles with ABS is because all the crud in the system settles into the caliper piston bore. When you push in the piston, you're pushing all that crud up into the ABS valves. It can clog the valves.

The correct way to depress the piston is to crack the bleeder valve and force the old fluid out the bleeder. Then close the bleeder as soon as the piston seats.

That way you're flushing the crud out, not backwards.

I work for GM, Specifically in the group that develops and tests ABS, traction control and stability systems. I have never seen or heard of a caliper like you describe. The calipers on ABS vehicles CAN be more difficult to compress due to the additional restriction in the brake lines caused by the small orifices in the ABS HCU (Hydraulic Control Unit). The comments about rear calipers are correct. On GM vehicles you need to "Screw" the rear caliper in instead of using a C clamp to compress it. You can tell your caliper works this way by looking at the face of the piston. There will be holes or indents in the face of the piston to allow the special tool to grab and rotate it. In a pinch I have used the tips of needle nose pliers to rotate the piston back into the caliper. The worst thing you can do when servicing an ABS equipped vehicle is to introduce air into the system. The orifices in the HCU can make it very difficult to properly bleed the system, depending on the design. There are also some systems that require a special bleed procedure using a scan tool with the correct program. These are usually only available at a dealership.

you will have to remove the brake line as the abs pump wont allow fluid back through it i wasted a whole hour before realizing this (not working from a manual)lol i think the bleeding valve is different.

  I just a few weeks ago replaced the front brake pads on my car, which has ABS.  I used the traditional C-clamp method to retract the calipers, and it worked just fine, and does not appear to have produced any adverse effects.  This is certainly the first that I have ever heard of any claim that this cannot or should not be done.

  GingerL's remarks concerning rear disc brakes may be true.  I do know that there are some complications introduced with rear disc brakes, because of the need to have a parking/emergency brake activated by cables, separate from the hydraulic brake system.  It's easier to implement this on drum brakes than on disc brakes, which is why most cars have drum brakes in back.  It may very well be that some of the methods used to implement a cable, actuated parking.emergency brake on a rear disc brake system may have the effect of preventing normal methods of retracting the caliper from working.

  I don't have any firsthand knowlege of this, as every car I have ever owned has had drums in back, and discs in front.