You'll need to use multiple sort conditions in your order by clause to handle this properly. The problem with this approach is that the performance will be bad when you have a lot of rows in the table because of that nasty sort operation.
Instead, you may be better off using dynamic SQL (as someone else suggested).
Declare @orderby varchar(100) , @direction varchar(10)
set @orderby = 'col1'
set @direction = 'desc'
select identity (int) as autoid, *
into #temp
from table
order by case when @direction = 'desc' and @orderby = 'col1' then col1 end desc,
case when @direction = 'asc' and @orderby = 'col1' then col1 end,
case when @direction = 'desc' and @orderby = 'col2' then col2 end desc,
case when @direction = 'asc' and @orderby = 'col2' then col2 end,
case when @direction = 'desc' and @orderby = 'col3' then col3 end desc,
case when @direction = 'asc' and @orderby = 'col3' then col3 end,
case when @direction = 'desc' and @orderby = 'col4' then col4 end desc,
case when @direction = 'asc' and @orderby = 'col4' then col4 end,
case when @direction = 'desc' and @orderby = 'col5' then col5 end desc,
case when @direction = 'asc' and @orderby = 'col5' then col5 end