No, it is not possible to do that except in the trivial case where you have just one entry in the comma-separated list.
Within the stored proc, you should split the comma-separated string into a virtual table and join to that table. There are string splitter functions available - an especially good one is here in Fig. 21: http://www.sqlservercentral.com/articles/Tally+Table/72993/ Copy that function, run it to install it and use it like in the examples on that page.
An alterative approach is to do something like the following:
','+@agelist+',' LIKE '%,'+CAST(age AS VARCHAR(8))+',%'Splitting the comma-separated list is a better approach from a performance perspective.
There are other ways of passing arrays to a stored procedure - see Sommarskog's article here: http://www.sommarskog.se/arrays-in-sql.html