Syncing individual items from iTunes to Android can be done by toggling a setting in iSyncr Desktop (USB) or your iSyncr app (WiFi). The option to sync only checked songs appears in iSyncr Desktop with a USB connection after iSyncr Desktop is opened, you can select "Options - Sync only Checked Songs".

Over WiFi, you can select "Tools - Settings - WiFi Sync - Sync Checked Songs".

Check or uncheck your items from iTunes. With this setting toggled and your items "checked" in iTunes we would expect only checked items be sync'd from iTunes to Android. In iTunes 12.4 check boxes are removed your iTunes items that are not checked appear as greyed out. Right-click items that you wish to check, then choose "Check Selection" or "Uncheck Selection". Press control and click to select multiple items.