But you said you have SQL Commandline... 
You may use this:
select top 100 --or any other top number
left(a.name, 50) as TableName,
left(b.name, 50) as IndexName,
c.rowcnt as Rows,
c.pagecnt*2 as DataKBytes,
c.leafcnt*2 as IndexKBytes,
c.pagecnt*2 + c.leafcnt*2 as TotalKBytes
from {YOURDB}..sysobjects a,
{YOURDB}..sysindexes b,
{YOURDB}..systabstats c
where b.id = a.id
and c.id = a.id
and c.indid = b.indid
order by 3 desc --or any other column from the result set
You can aggregate it with sum() on each numerical column and add group by left(a.name, 50), left(b.name, 50) to have it displayed in one row per one table - if you don't want break down by indices... You might want to run sp_flushstats to flush in-memory statistics to disk first - but you will probably not be able to, so expect imprecision.
Have fun...