if that doesn't work out and you know in advance the number of columns required for your cross-tab then consider creating a mock cross-tab. you don't need to know the number of rows as this would be dynamic.
as an example, if you've got a group on product name, and you want to create a mock cross-tab with one column per year, create a set of formulas, one for each year...
e.g. CurrentYear
if year({your date field}) = year(currentdate)
then {your order amount field}
this field would be placed in the details section and summarized on the group level.
e.g. Lastyear
if year({your date field}) = year(currentdate) -1
then {your order amount field}
this field would also be placed in the details section and summarized on the group level.
and keep creating as many formulas (and adding the summaries) as you need columns in your report.
it's a bit of work, but if it's one of the only available options, then it may be worth the extra time.