In Sql Server 2005, you can use the sp_startpublication_snapshot stored procedure to achieve this, using the following format:
sp_startpublication_snapshot [ @publication = ] 'publication'
[ , [ @publisher = ] 'publisher' ]
(omit the publisher out if you are using a SQL Server publisher).
I do not know if this is appropriate to Sql Server 7 or 2000 though.