Unfortunately, there isn’t, to the best of my knowledge (apparently, I’ve managed to not get a pull request successfully set up.). I’ve cloned & modified the standard kickstart template to add my own repos. The call to the following snippet is inserted in the template where repositories would be added. You’ll also need a parameter implemented as an array of hashes.
< %#
kind: snippet
name: Custom repositories
model:
snippet: true
%>
<% if host_param("custom_repos") %>
<% host_param("custom_repos").each do |repo| %>
repo --name=<%= repo['name'] %> --baseurl=<%= repo['uri'] %>
<% end %>
<% end %>