Ok, I've managed to find a hacky solution to this problem. To clarify, the original problem was not concerned with how to add variables/tokens into a saved search, but how to call a saved search using a token generated from a Pulldown module.
Now since we can't pass parameters into the savedSearch param of a HiddenSavedSearch module, you can instead use a Search module to call the saved job (with the included token):
<module name="Search">
<param name="search"> | loadjob savedsearch="user:app:MySavedSearch"</param>
...
</module>
Where I would have something like:
| loadjob savedsearch="admin:search:$token$"
Note that this command will load the previously run job (if it exists) as opposed to starting a new job automatically (which the savedsearch command does).
The splunk documentation for loadjob can be found here:
http://docs.splunk.com/Documentation/Splunk/latest/SearchReference/Loadjob
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