There are several good resources for using Perl with the eBay API
Net::eBay Perl Module
This project wraps both legacy API and new API access to eBay functionality, by providing a Perl module that encapsulates low level details. Note that the legacy API is no longer supported by eBay.
Please create a file named eBay.ini with the contents below:
# dev or prod
SiteLevel=prod
# your developer key
DeveloperKey=################
# your application key
ApplicationKey=##################
# your certificate key
CertificateKey=###################
# your token (a very BIG string)
Token=YourTokenHere
Please find the code samples in the Net-eBay-0.xx package or the ones attached.