Content packages are just zips containing two major pieces - the imsmanifest.xml and the content. The manifest file tells the LMS how the content is organized (like the table of contents in a book) and what resources make up the content/course (like a packing slip). And the content is what the LMS shows to the learner as the course, basically SCOs (generally web pages, swf, etc) and assets (images, pdf, supporting stuff).
What Brian G is saying is that the resources that make up the content might not be able to be modified, they could be swfs from a flash project or some other compiled software.
But that doesn't mean you can't add sequencing or other content, you just need to unzip the content package, modify the manifest right, add your new SCOs, and zip up your new content as a package.
Say for instance you have a package that has 3 SCOs and you want to add an intro page. You can do that by adding another <item>
to the <organization>
and then the path to what the LMS would deliver <resource>
under <resources>
.
<organizations default="course">
<organization identifier="course">
<title>The course</title>
<!-- add another item for your intro -->
<item identifier="intro" identifierref="INTRO">
<title>Introduction</title>
</item>
<item identifier="sco1" identifierref="SCO1">
<title>SCO 1<title>
</item>
<item identifier="sco2" identifierref="SCO2">
<title>SCO 2<title>
</item>
<item identifier="sco3" identifierref="SCO3">
<title>SCO 3<title>
</item>
</organization>
</organizations>
<resources>
<resource identifier="INTRO" type="webcontent" adlcp:scormType="sco" href="scos/my_intro.html">
<file href="scos/my_intro.html" />
<!-- possible other needed files, or other resources needed -->
<dependency identifierref="APIWRAPPER" />
</resource>
<resource identifier="SCO1" type="webcontent" adlcp:scormType="sco" href="scos/sco1.html">
<file href="scos/sco1.html" />
</resource>
<!-- other sco resources -->
<resource identifier="APIWRAPPER" type="webcontent" adlcp:scormType="asset">
<file href="assets/APIWrapper.js" />
</resource>
</resources>
ADL modified an open source project to do content packaging. It's called Reload and it is designed to help you create the manifest and package your content. It also will open existing packages and allow you to make edits. You can download it here http://www.adlnet.gov/wp-content/uploads/2011/07/ADL_SCORM_2004_RELOAD_Editor_1_1.zip
.. There's also more resources and info on ADL's site: http://www.adlnet.gov/scorm/ .
The CAM book in the SCORM Document Suite has all the gritty details about packaging your content. The SN book goes over everything to know about sequencing. You can find the books here: http://www.adlnet.gov/wp-content/uploads/2011/07/SCORM_2004_4ED_v1_1_Doc_Suite.zip
Another resource by ADL are the Content Developer and ISD guides. They have tips, guidance, and examples for developers working with SCORM. http://www.adlnet.gov/scorm-users-guides-for-instructional-designers-and-programmers-are-now-available/