Admission to the BTech course through Lateral entry after Diploma in West Bengal is only provided on the basis of JELET. Now it means that you won't be able to give the examination although I would recommend you to contact the private colleges of your choice and get it discussed. Sometimes some private engineering college have exceptional course through which you may seek admission. Although I don't think that will be possible. But take a try.

To know more about JELET visit the link below:

https://www.careers360.com/exams/jelet

I hope this answer helps. All the very best for your future endeavors!