Help with basic keybind saving a variable

[sinnereso]

Hey guys im looking to convert a section of code im currently using and having to manually edit into a press and hold for 1-2secs keybind to save a target or user @name variable for it. Any suggestions? heres what ive got right now:

<Bindings>
<Layer name="SI_KEYBINDINGS_LAYER_GENERAL">
<Category name="|c9900FFRidinDirty|r">
<Action name="MOUNT_USER">
<Down>UseMountAsPassenger("@NAME")</Down> <!-- EDIT FOR DESIRED TARGET @NAME -->
</Action>
</Category>
</Layer>
</Bindings>