Without really knowing the intimate details of your accounting system, I can only give a generalized answer.
What I would do is create a few "real" tables, not a temp tables since it seems this will be a continual process.
The first table to create would be a work table that you may want to call something like ADPImport. The fields in this table should match the fields the ADP file has. We can now import the text file into this ADPImport table either by DTS or OSQL. I prefer DTS since you can manipulate and port the data in various fashions to fit your needs. It is also much more powerful than an OSQL command(s).
Now come the part on setting up the records to match your accounts. Here I cannot help because I am not familiar with your system.
In the most general form, you will use sets of INSERT INTO ... SELECT FORM statements to grab the records based on a GL Code and insert them into your transtable.
You can accomplish all of the needed tasks within a DTS package. The issue at hand is having someone versed in your accounting process who knows a bit about SQL Server and DTS.
The other table I probably would create would be a history table. Maybe ADPImportHistory. This table would match the ADPImport table exactly except maybe a datetime field, if once does not already exist, for the date we imported the records. After your process is complete, you could export the ADPImport table to the ADPImportHistory table, set the import date field to the run date, and then you could have a complete history of the transactions that were imported into your accounting system.
Sorry for not going into too much detail, but I just wanted to get across the basic idea of what needs to be accomplished. Hope this help some. Good Luck!
Thanks
J. Kusch