totally untested, just wrote this here, probably won't work on the first try:

robot.hear /(?:gh|github) issue #(\d+)(?: in ([\w\d-_]+)(?:\/([\w\d-_]+))?)?/i, id:'gh-issues.mention', (msg) ->
  id = msg.match[1]
    repo = if msg.match[2]? and msg.match[3]?
    "#{msg.match[2]}/#{msg.match[3]}"
  else if msg.match[2]?
    "#{DEFAULT_OWNER}/#{msg.match[2]}"
  else
    "#{DEFAULT_OWNER}/#{DEFAULT_REPO}"
  robot.ghissues.showIssue msg, id, repo

So you should then be able to mention issues in a chat:

User> So I says to Mabel, I says check out gh issue #4832742 in hubot-scripts/hubot-gh-issues
Hubot> Issue #4832742 in hubot-scripts/hubot-gh-issues - foo - https://github.com/hubot-scripts/hubot-gh-issues/issue/4832742

@benwtr thanks for the enterprise token help.
I'm getting the "bad credentials" error above, but have verified that my token is valid.

I start my hubot like: HUBOT_GITHUB_TOKEN_FERNET_SECRETS={my token fernet secret} HUBOT_GH_ISSUES_DEFAULT_OWNER={email address to my GitHub enterprise account (from where the oath token is generated)} HUBOT_GH_ISSUES_DEFAULT_REPO={organization name} ./bin/hubot

If I run hubot github token verify it returns: "Your GitHub token is valid on github.{my enterprise}.com."

But if I run hubot github show issue #247 I get the error Hubot> Shell: Error from GitHub API: Bad credentials. Have I done something wrong? or any thoughts on how I can start debugging this/looking?