It is available, but not simple to implement - are you sure you don't want to do it the other way around? (Make Splunk part of your web portal?)
The forward way around:
1) Create a splunk app with all your Splunk capabilities
2) Create a module under appserver/modules/<your module name> that implements the control. You'll have HTML, CSS and JS scripts, plus a conf file for implementation
3) Put the control (via the module) on the right page.