Auto Installing WordPress With WHMCS

I am offering wordpress only hosting.

I am using WHMCS to auto-create client accounts in WHM from my website. The accounts created are given a sub-domain as their new web address.

What I would like to do is auto-install wordpress on this sub-domain using PHP. My host does not use Softaculous so the extension available as a WHMCS add-on is unusable.

Any other ways I can implement? Thanks in advance.