I don't think it is possible to modify the modifyTimestamp in a supported manner.
When you are using LDAP to view Objects in eDirectory you may have noticed the ModifyTimestamp.
This attribute is helpful if you are checking if something has been changed in a period of time. However if you look in eDirectory or query eDirectory in IDM for this attribute you will not find it.
The ModifyTimestamp you see in the LDAP view is actually the Timestamp of the modifiersName attribute in eDirectory.
You can query the attribute in IDM following the next steps:
Query modifiersName of an object into a local variable as a nodeset.
With XPATH you can use [local variable]/@Timestamp to get the modifyTimestamp.
I just did this. My inspiration was this though (https://ldapwiki.com/wiki/IDM%20Tricks).
Now searching for a way to modify timestamp I found this great tip, that would save me time if I found it earlier.
I used timestamp to report on users who have not changed some attributes in a certain amount of time.
Now I want to test my implementation and I am wondering if there is some way to change the value of timestamp (like back in time). I know very counter intuitive, but still, I want to test that the implementation is working...