My first response would be: Do you really have a need for 255+ columns? Very often it is a failure in database design, data normalization. Not always but often.

Note: In the late 1990's I discovered that where DataFlex had a limit of 255 columns Oracle had a limit on 253 columns. I just googled on the maximum and found a post titled How to Optimize design a 1000+ columns in a Oracle DB and in there the replier suggest to split tables in < 255 column tables.