Okay, assuming you enter your data into column C, starting at C2, then
put this formula in D2:

=VALUE("0:"&INT(C2)&":"&MOD(C2,1)*100)

and format the cell using custom set to [m]:ss. You can then copy this
formula down several rows.

Now if you have a time like 10:33, you enter 10.33 in column C and this
will be converted to time format in column D. Once you have entered the
data, you can fix the values in column D using paste special and
values, and then delete column C.

Hope this helps.

Pete