*/5+2 * * * * 1st-script
*/5+4 * * * * 2nd-script
For future reference take a look at this online Cron Job Generator.
Since there are several reports that the + syntax is not working on Ubuntu 14.04, here’s a variation:
2-59/5 * * * * 1st-script
4-59/5 * * * * 1st-script
This will result in the 1st script to run every 5 minutes starting with an offset of 2 minutes at the beginning of each hour and the 2nd script to behave the same with an offset of 4 minutes.