The following are the list of few institutes, I know that will accept CAT scores and are comparable with IIM's.. I guess this would be of some help to you

• Institute of Management Technology (IMT), Ghaziabad
• Management Development Institute (MDI), Gurgaon

Others which fall in a category below these include:

• Bharathidasan Institute of Management (BIM), Trichy
• FORE School of Management, New Delhi

And the insitutes which fall below the institutes mentioned above in their ranking but accept CAT score

• Birla Institute of Management Technology, NOIDA
• Delhi School of Economics (DSE), Delhi
• Department of Financial Studies (DFS), University of Delhi, South Campus
• Indian Institute of Forest Management (IIFM), Bhopal
• Indian Institute of Science (IISc.), Bangalore
• Indian Institute of Social Welfare and Business Management (IISWBM), Kolkata
• Indian Institute of Technology, Kanpur (IIT-K)
• Institute of Management Development and Research (IMDR), Pune
• Institute of Management Technology (IMT), Dubai Campus
• Institute of Technology & Management (ITM), Mumbai
• Loyola Institute of Business Administration (LIBA), Chennai
• Nirma University Institute of Management, Ahmedabad
• Symbiosis Institute of International Business (SIIB), Pune
• Sydenham Institute of Management Studies and Research and Entrepreneurship Education, Mumbai
• Welingkar Institute of Management, Mumbai