Using cellranger for non-10x data
Possible?  Sure.  Your biggest problem is that 10x is expecting barcodes from its whitelist.  I used to alter the python scripts to accept a 'new' kind of chemistry where the barcodes and umi lengths matched what I had, but I found that my modifications stopped working when the version updated,  and I couldn't figure it out, so I started modifying fastqs instead.