Modify a WP Plugin

Need a small change in this plugin - [login to view URL] It has slots of time defined when posts of all categories are scheduled. I need a little change in it, so that one category posts are scheduled as per the time slots defined in the plugin, whereas the 2nd category posts are scheduled 10 hours and 30 minutes later to the slots (different timezone). So if we have 3 slots defined in plugin as 8 am, 1pm and 5 pm, posts from 1st category will be scheduled at these times while the posts from 2nd category will be scheduled at 8am + 10H:30M later and so on. Install the plugin and check how it work and let me know if you can do it. Please include "SchedulePoster" in your bid so that I know you read through the description. Needed it to be done asap, so only bid if you can deliver it in a day or two. Shouldn't take more than a day and few lines of code modification for right candidate.