I found a solution
InputAccel Server stores all Settings that differ from default settings in IADB.
If you want to change server settings, just add or adjust a row to tbl_ServerConfig referencing the server (have a look at tbl_server) and setting name (SCName). Settings only take effect after restart of InputAccel Server, because you only change startup settings.
For example to set BatchMaxAdressSpaceK to 16 GByte (16GB * 1024MB/GB * 1024KB/MB = 16777216KB) for the first InputAccel Server just add the following row:
SCServerId = 1
SCName = “BatchMaxAdressSpaceK”
SCValue = “16777216”
SCRowModifiedDttm = CURRENT_TIMESTAMP
SCRowVersion = 0
If Setting for the server already exists just update including an increment for SCRowVersion.