You will need to make the CA DB2 Tools' RSPxxxx clist members addressable to your ISPF environment by copying them from our .CDBACLS0 (clist) library to one of your clist/exec libraries defined in the SYSPROC concatenation (as revealed when invoking TSO ISRDDN from the command line).
The RSPxxxx members to be copied are RSPMAIN, RSPDEF, RSPINIT, and RSPUSER.
You then will need to edit the RSPMAIN clist's PROC statement to provide the following information:
PROC 0 HIGHLVL(CA DB2 Tools' dsn highlevel) +
Then from ISPF option 6 command shell enter RSPMAIN
This will take you directly into the CA DB2 tools main menu.