This sounds like a job for OUTPUT parameters within your stored procedure.
http://technet.microsoft.com/en-us/library/ms187004(v=sql.105).aspx
I don't know of any possibility to handle plural result-sets within T-SQL, as far as i know it's strictly designed to handle only singular results - and since you can't edit the Stored Procedure itself, you should work with the result within the language you are using to process the information from SQL. I can provide an example for ColdFusion, i guess there are similar approaches possible for most other languages.
<!--- This calls the procedure --->
<cfstoredproc procedure="usp_GetCustInfo" datasource="your_ds">
<cfprocparam cfsqltype="cf_sql_varchar" value="1" />
<cfprocparam cfsqltype="cf_sql_varchar" value="Some Parameter" />
<cfprocresult name="local.table_1" resultset=1 />
<cfprocresult name="local.table_2" resultset=2 />
</cfstoredproc>
<cfdump var=#local.table_1# title="Result Table 1">
<cfdump var=#local.table_2# title="Result Table 2">