Custom Lifecycle Interval (something between visit and visitor)

So for pathout reports it seems there are two 'lifecycle' levels:

• a visit/session (defined as a browsing session ending by 30 minutes of inactivity or exit of the site)
• a visitor (defined via unique visitor id stored in a persistent cookie)

My question is could I have a custom interval defined (i.e. purchasing lifecycle) so that I can set a key-value pair in the cookie, then reset the value whenever a critical event has happened

basically trying to track behavior by a single visitor, across multiple visits within a custom defined 'interval'