Single SQL query

I need some one can make this: I need get some data from a table, taking last 8 week. But the week grouped that i need is like from last week tuesday to this week monday. example: normal week start on sunday and end on saturday in the same week. But, the week i'm needing is starting this tuesday and end next monday. So using this type of week get last 8 week of data. Beside, i need pass any date and you get the week and start get data from last 8 week using my type of week. if you already got the query just let me know. Note: i dont need you make the query on my data, i just need the query or function working!!!! any question, let me know!!! Budget: $20