T-SQL (SS2K8) :: Concatenate Specific Values From A Column

Give this data set;

declare @BO table (Col1 varchar(50), Col2 varchar(50))
insert into @BO values
('01','009920140516102116'),
('071710811019600001000005',''),
('070534524264000001000005',''),
('001806505517000001000005',''),

[Code] ....

select * from @BO

The 2 digit number that appears on line 1, 7 and 13 (only in this example) i need to have added to the begin of each value below it until the next 2 digit number is encountered. The desired result set would look like:

declare @BOD table (Col1 varchar(50), Col2 varchar(50), col3 varchar(50))
insert into @BOD values
('01','009920140516102116',''),
('071710811019600001000005','','01071710811019600001000005'),
('070534524264000001000005','','01070534524264000001000005'),

[Code] ....