Would this work?
(string value of property "HotFixID" of it | "None", string value of property "InstalledOn" of it | "None") of ((select objects "* from Win32_QuickFixEngineering" of WMI) whose (((it as date) of ( ((it as integer as string) of preceding text of last "/" of following text of first "/" of it ) &" "& (preceding text of first "/" of it as integer as month as three letters)&" "& (following text of last "/" of it as integer as string)) of string value of property "InstalledOn" of it) > (january 1 of 2015)))
This is three pieces:
Getting the HotFixID and Installed On:
(string value of property "HotFixID" of it | "None", string value of property "InstalledOn" of it | "None") of
Getting the HotFixes from WMI:
(select objects "* from Win32_QuickFixEngineering" of WMI)
Converting InstalledOn into a date object and then comparing against a given date:
((select objects "* from Win32_QuickFixEngineering" of WMI) whose (((it as date) of ( ((it as integer as string) of preceding text of last "/" of following text of first "/" of it ) &" "& (preceding text of first "/" of it as integer as month as three letters)&" "& (following text of last "/" of it as integer as string)) of string value of property "InstalledOn" of it) > (january 1 of 2015)))