From the docs:
Building an app for Ad Hoc
distribution is similar to building an
app for App Store distribution, with
an exception of two additional steps.
First, you need to create an Ad Hoc
Distribution Provisioning profile and
add the UDIDs of the iOS devices that
you want to distribute to using the
iPhone Developer Program Provisioning
Portal. Second, you need to create a
code-signing Entitlements file. For
information about how to create an
Entitlements file read the Managing
Application Entitlements section of
the iOS Development Guide.
Managing Application Entitlements
iOS provides access to special
resources and capabilities—such as
whether your application can be
debugged—through properties called
entitlements. To specify entitlement
information in your application, you
add an entitlement property-list file
containing entitlement definitions
(key/value pairs) to your project.
When you build your application, Xcode
copies the file to the generated
application bundle.
To add an entitlements property-list
file to your project:
In the Groups & Files list, select the
Resources group. Choose File > New
File. Choose the iOS > Code Signing >
Entitlements template. Name the file
Entitlements.plist. (You can use any
name; just ensure it matches the value
of the Code Signing Entitlements build
setting, as explained later in this
section.) Set the type of the
property-list file to iPhone
Entitlements. With the file selected
in the text editor, choose View >
Property List Type > iPhone
Entitlements plist.
Add your entitlement entries to the
file. For each entitlement property
you need to define:
Click the Add Child or Add Sibling
buttons to the right of the selected
row. The Add Child button has three
lines depicting a hierarchy, the Add
Sibling button has a plus (+) sign on
it. Choose the entitlement property
from the pop-up menu that appears. If
the entitlement you need to add
doesn’t appear in the menu, choose
View > Property List Type > Default
for File Type. Then enter the
entitlement-key name and type.
Enter the value for the property. Set
the Code Signing Entitlements build
setting for the target to the name of
the newly added entitlements
property-list file.
Once you
have created your Entitlements file
and added it to your Code Signing
Entitlements build setting, open the
Entitlements file and add or edit the
get-task-allow key and set it to
false.
In addition to compressing your .app
bundle to distribute your Ad Hoc build
to testers, etc. it is recommended
that you also compress the
provisioning profile before
distributing because certain email
clients and servers may corrupt the
provisioning profile.
For information about Ad Hoc
distribution please read the
Publishing Applications for Testing
section in the iOS Development Guide.
