Step 1. Visit the vSphere SDK for Perl Home Page

• vSphere SDK for Perl

You will find latest Downloads, Reference Documentation and Community Discussions and links to resources.

Step 2. Become familiar with vSphere SDK for Perl Resources:

• Support Information: vSphere, VI 3.x SDK - Support Information
• VMware Code Central (Sample Code) : vSphere SDK for Perl
• Take a look at Getting Started with vSphere SDKs document

Step 3. Explore new ways of managing your vSphere Platform using the remote CLI

• Try some of the esxcfg-* commands bundled with the vCLI/RCLI

Additional utilities bundled with vCLI/RCLI installation

• vSphere SDK for Perl utility documentation
• VI Perl Toolkit utility documentation

Step 4. Develop and create your own scripts and utlities using the vSphere SDK for Perl
Become familiar vSphere 4.0 API Reference documentation

• vSphere 4.0 API Reference
• VI 3.5 API Reference

Step 5. Learn how to get started with writing your own Perl script using vSphere SDK for Perl

• This VMware document is a little out dated but it still all applies to writing your own Perl scripts using the vSphere SDK for Perl

Step 6. For more scripts developed against the vSphere SDK for Perl, check out the vGhetto Script Repository for more examples!
I think the easiest way to learn this is to start playing with some of the canned scripts and to make it even easier to have an environment that's all setup for you with both the vCLI and vSphere SDK for Perl, you can download VMware vMA.