The Thomson Reuters Insiders have a cusip variable (the first 6 digits of the cusip code). It is the issuer code and is "historical".
On the other hand, Compustat's 6-digit-cusip is named CNUM. However, it is a "header" variable (only valid for the latest observation of the series). Compustat assigns this CNUM to all the observations of the firm.
Matching those sets can be done using those cusips. However, we do not have a sample program either can we conclude how good the matching procedure is.
For more information on Thomson Reuters Insiders, you can check our overview: Overview of Thomson Reuters Insiders in WRDS.